Class - VI BIOLOGY (Non IAS)
Chapter – 1
Life on Earth – 1 : Characteristics of the living
TEST YOURSELF
1. Are there any common features between living and non living things? List such features.
Ans: Yes. Living and non living things possess mass, shape and occupy space. Both are made up of
basic structural units – cells in the living and molecules in the non living things.
2. Mention two features in which plant cells differ from animal cells.
Ans:
Plant cell
Animal cells
1. Cell wall is present.
Cell wall is absent.
2. Chloroplast is present.
Chloroplast is absent.
3. Distinguish between life-cycle and life span.
Ans: Life- cycle: The cycle of birth, growth, reproduction and death. Living things start their life from a single cell. In case of animals, life-cycle can be represented as Birthà Growthà Reproductionà Death.
In plants, life-cycle begins from seeds or spores.
Life span: The period during which the life-cycle is completed is called the life span.
4. Define the following terms:
Ans: 1. Stimulus: Anything which produces a response in an organism is called a stimulus.
2. Phototropic: The movement of the shoot system of a plant or organisms towards the light is
called phototropic.
3. Geotropic: The movement of the root system of a plant downwards, towards the soil is
called Geotropic .
4. Response : An activity in the living body that results from a stimulus is called response.
5. Name the following:
Ans: 1. Waste products produced in plants: Carbon dioxide and water vapour.
2. Waste products produced in animals: Urine, Sweat and Carbon dioxide.
6. Name the instrument used to study microorganisms.
Ans: Microscope.
7. Name 3 microorganisms.
Ans: Yeast, Virus and Penicillium.
8. How are plants different from animals?
Ans:
Plants
Animals
NUTRITION
1. Most plants can prepare their own food (they contain a green-pigment- chlorophyll) - Autotrophic nutrition.
1. Animals cannot prepare their own food (lack chlorophyll) Heterotrophic nutrition.
LOCOMOTION:
2. They are generally fixed to the soil. Locomotory organs are absent.
2. Show locomotion, possess organs for locomotion (legs, fin, feathers etc.)
GROWTH
3. Unlimited growth, it is localized at the tips of roots or stems
3. Growth is limited and diffused.
CELL STRUCTURE
4. Possess cell wall and chloroplasts
4. Cell wall and chloroplasts are absent.
9. Mention two features in which plant cells differ from animal cells.
Ans:
Plant Cell
Animal Cell
1. Cell wall is present.
1. Cell wall is absent
2. Presence of chloroplasts.
2. Absence of chloroplasts.
10. Name an organism having characteristics of both plants and animals.
Ans: Euglena.
II. Answer the following questions:
1. Which of the following are living objects? Milk, honey, orange, hen’s egg and curd.
Ans: Hen’s egg
2. A motor car moves, takes in oxygen and gives out carbon dioxide, consumes fuel but is not a living creature. In what ways does it not qualify as a living organism?
Ans: A motor car does not show the other characteristics of living things like cellular organization, growth, reproduction, response to stimulus and life cycle.
3. Name a plant which is not green and an animal which does not move about freely.
Ans: Non green plant – Mushroom.
An animal which does not move about freely – Sea anemone.
4. Name one microscopic plant and microscopic animal .
Ans: Microscopic Plant - Penicillium Microscopic Animal – Amoeba
5. Why do living organisms need food?
Ans: 1. Food provides us with energy so that we can do various activities.
2. Food helps in the growth of the body as well as in its maintenance and repair.
6. Which part of leaf takes part in exchange of gases?
Ans: Stomata.
7. List out the differences between living and non-living things.
Ans:
Characteristics
Living Things
Non – living Things
1. Cellular organization
2. Nutrition
3. Respiration
4. Growth
5. Excretion
6. Reproduction
7. Response to stimuli
8. Life cycle
Are made up of cells.
Require food for growth and development.
Show respiration.
Is permanent and irreversible.
Removal of waste materials takes place.
Takes place.
Present.
Consists of birth, growth, reproduction and death.
Lack cellular organization.
Not required.
No respiration.
Lack growth; even if present it is reversible.
No excretion.
No reproduction.
Absent.
Lack a life cycle.
Chapter – 2
Life on Earth – II : Classification of Living Beings
I. Test yourself:
1. Define:
(i) Classification: The grouping together of living things on the basis of similarities and their separation on the basis of differences is called classification.
(ii) Species: Species is a group of similar organisms which resemble one another more than they resemble the members of other species and they can reproduce among themselves.
[iiI] Invertebrates: The animals which do not have a backbone or bony skeleton are called invertebrates. Ex.: Snail
[iv] Vertebrates: The animals which have a backbone or vertebral column are called vertebrates. Ex.: Man
[v] Holozoic animals: The animals which consume the whole food into their body and digest it are called holozoic animals. Ex.: Cow
[vi] Herbivore animals: Animals which eat only plants are called herbivores. Ex.: Goat
[vii] Carnivore animals: Animals which eat other animals are called carnivores. Ex. : Lion
[viii] Omnivore animals: Animals which eat both plants and other animals are called omnivores. Ex.: Man
[ix] Parasite: The organisms that live on other organism and also depend on that organism for their food are called parasites. Ex. Malarial parasite – It lives inside the body of a man.
(x) Heterotrophic nutrition: Nutrition derived from other organisms (dead or living) as in animals, fungi and some bacteria is called heterotrophic nutrition.
2. Give four examples each of
(i) Vertebrates : Fish, frog, man, elephant,
(ii) Invertebrates : Butterfly, earthworm, mosquito, amoeba.
3. Name the largest group of invertebrates.
Ans: Arthropoda.
4. Give two examples of each of the following.
Ans: (i) Egg – Laying animals – Hen, Fish
(ii) Animals producing young ones- Lion, Cat
5. Mention the character on the basics of which animals are classified into vertebrates and invertebrates.
Ans: Based on the presence or absence of back bone or vertebral column, animals are classified into vertebrates and invertebrates. The animals with a back bone are called vertebrates and those without a back bone are called invertebrates.
6. Name the different major groups of invertebrates, giving two examples for each.
A.
Major Groups
Examples
1. Protozoa
Amoeba, Euglena
2. Porifera
Sponges, Euplectella
3. Coelenterata
Hydra, Sea Anemone
4. Helminthes
Flat worms, Round Worms
5. Annelida
Earthworm, Leech
6. Arthropoda
Cockroach, Crab
7. Mollusca
Snail , Mussel
8. Echinodermata
Star fish, Brittle Star
7. Name the major groups of vertebrates. Give two examples of each group.
A.
Major Groups
Examples
1. Pisces
Rohu, Shark
2. Amphibia
Frog , Toad
3. Reptiles
Snake, Lizard
4. Aves
Peacock, Sparrow
5. Mammals
Porcupine, Kangaroo
8. Define :
(i) Flowering plants : The plants which bear flowers and fruits are called flowering plants Ex : Sunflower, Mango.
(ii) Non – flowering plants : The plants which do not bear flowers are called non – flowering plants Ex : Mushroom, fern.
[iii] Herbs : The small plants with soft stems are called herbs. Ex. Sunflower, Paddy
[iv]Shrubs: Medium sized plants with hard and woody stems are called shrubs. The branches often
arise just above the ground. Ex. : Rose , Hibiscus etc.
[v] Trees: Tall trees with hard and woody branches and a main trunk are called trees. Ex.: Banyan,
Mango etc.
vi] Annual plants: Plants which complete their life cycle in one year from seed to flower, fruit and
seed and then die are called annual plants or annuals. Ex.: Most of the herbs.
[vii] Biennials : Plants which complete their life cycle in two years are called biennials or biennial
plants. These plants grow in the first year and in the second year they produce
flowers, fruits and seeds. Ex.: Radish, Carrot.
[viii] Perennial plants: Plants that live for many years are called perennials. They produce flowers,
fruits and seeds every year. Ex.: Mango, Guava etc.
[ix] Saprophytes: The organisms that feed on dead remains of plants and animals are called
Saprophytes. Ex. Yeast and mushroom.
[x] Xerophytes: The plants that live on land having scarcity of water, as in a desert are called
xerophytes. Ex.: Cacti , Babool, and Ber.
[xi] Hydrophytes: The plants that live in water are called hydrophytes. Ex. : Lotus, Hyacinth , Algae.
9. How are plants classified? Name the 2 groups of plants.
Ans: Plants are classified based on the presence or absence of flowers. Plants are of two groups. They are Flowering and Non-flowering plants.
10. Name the major groups of non flowering plants. Give two examples of each of the group.
A.
Major Groups
Examples
Non- flowering plants
1. Bacteria
Escherichia coli, Diplococcus pneumoniae.
2. Algae
Chlamydomonas, Spirogyra, Volvox, Seaweed.
3. Fungi
Yeast, Mucor, Rhizopus (bread mould), mushroom.
4. Bryophyta
Liverworts and mosses.
5. Pteridophyta
Ferns, horse- tails.
11. Write about the binomial system of naming organisms.
Ans: The system of naming plants and animals by using two words i.e. Generic name and Specific name is called Binomial system. This was introduced by the Swedish botanist Carolus Linnaeus.
Ex.; The scientific name of Human beings is Homo sapiens, wherein ‘Homo’ is the genus
name and ‘sapiens’ is the species name.
12. Give two examples of each of the following:
A.
Plants
Examples
1. Algae
Chlamydomonas, Spirogyra
2. Fungi
Mushroom, Rhizopus
3. Gymnosperms
Cycas, Pinus
4. Angiosperms
Tomato, Mango
5. Dicotyledonous plants
Ground nut , Green gram
6. Monocotyledonous plants
Rice, Wheat
7. Herbs
Paddy, Wheat
8. Shrubs
Rose, Hibiscus
9. Autotrophic
Coconut, Orange
10. Parasitic
Cuscuta , Viscum
11. Hydrophytes
Lotus, Hydrilla
12. Mesophytes
Neem, Custard Apple
II. Answer the following questions:
1. Why do we need to classify living organisms?
Ans: We need to classify living organisms because-
[i] classification makes the study of living beings simpler and easier.
[ii] it helps in easy identification of different organisms.
[iii] relationship between different organisms can be known easily.
[iv] it helps in tracing the possible origin of the organisms.
2. Why are scientific names better than their common names?
Ans: The common names of a species often varies with the languages and regions of the world. For eg. ‘Onion’is called ‘Piyaz’ in Hindi and Bengali, ‘irrruli’ in Kannada, ‘ullipaya’ in Telugu, ‘Ulli’ in Malayalam and ‘venagayam’ in Tamil. The local names of a species in one country or in one region of a country may not be understood by the people in other countries or other regions of a country. So we need to have an internationally accepted system of naming a plant or an animal. In scientific system an organism is known by two names – Genus name and species name. By this system the name of a species can be understood by people all over the world. Hence scientific names are better than common names.
3. Write the scientific names of 5 commonly available plants and animals.
A. ANIMALS:
Common Names
Scientific Names
1. Frog
Rana tigrina
2. Man
Homo sapiens
3. Housefly
Musca domestica
4. Peacock
Pavo cristatus
5. Indian tiger
Panthera tigris
PLANTS:
Common Names
Scientific Names
1. Mango
Mangifera indica
2. Banana
Musa sapientum
3. Onion
Allium cepa
4. Rose
Rosa centifolia
5. China Rose
Hibiscus rosa-sinensis
4. Give two examples of parasitic animals.
Ans: Mosquito, Leech.
5. Name two herbivores and two carnivores.
Ans: Herbivores – Sheep, Elephant
Carnivores – Lion, Tiger.
6. Classify the following animals into their respective groups:
1] Snail – Mollusca 10] Butterfly – Arthropoda
2] Amoeba – Protozoa 11] Whale - Mammal
3] Hydra – Coelenterata 12] Frog - Amphibia
4] Earthworm – Annelida 13] Cow - Mammal
5] Starfish – Echinodermata 14] Prawn - Arthropoda
6] Sea-Anemone – Coelenterata 15] Sponge - Porifera
7] Cockroach – Arthropoda 16] Bat - Mammal
8] Roundworm – Helminthes 17] Crcodile - Reptiles
9] Spider – Arthropoda 18] Crow – Aves
19] Shark – Pisces
7. Classify the following plants into herbs, shrubs and trees.
Ans: 1] Neem - Tree 6] Jasmine - Shrub
2] Mango - Tree 7] Oleander - Shrub
3] Palm - Tree 8] Mustard - Herb
4] China – Rose- Shrub 9] Sunflower - Herb
5] Rose - Shrub 10] Tulsi - Herb
11] Henna - Shrub
8. Classify the following plants into their respective groups.
Ans: 1] Grass – Annual 5] Radish – Biennial
2] Pea - Annual 6] Rose – Perennial
3] Guava – Perennial 7] Balsam – Annual
4] Neem – Perennial
9. Classify the animals on the basis of their body covering or coat, giving examples.
Ans: Based on body covering, animals can be classified into four groups. They are :
[i] Animals with scales – Ex. Snakes, Fish
[ii] Animals with feathers – Ex. Birds
[iii] Animals with slimy skin – Ex. Frog
[iv] Animals with hair or fur – Ex. Sheep or any mammal
10. Classify the following plants into their respective groups.
Ans: 1)Fern – Pteridophytes 7] Sunflower - Angiosperm
2] Cycas – Gymnosperms 8] Water Lily – Angiosperm, Hydrophyte
3] Neem – Angiosperms 9] Lotus – Angiosperm, Hydrophyte
4] Yeast – Fungi 10] Moss – Bryophyta
5] Mushroom – Fungi 11) Mango – Dicot
6] Spirogyra - Algae 12) Maize – Monocot
III. Give the differences between :
1. Invertebrates and vertebrate animals.
Ans: Invertebrates :The animals which have no back bone or bony skeleton are called invertebrates.
Ex : Cockroach, starfish.
Vertebrate : The animals with a back bone are called vertebrate animals. Ex : Lion, cat.
2. Warm blooded and cold blooded animals.
Ans: Warm Blooded Animals: The animals in which the temperature of the body remains constant and does not change with the change in the temperature of the environment are called warm blooded animals. Ex.: Man , Cat, Lion , Tiger etc.
Cold Blooded Animals: The animals in which the temperature of the body changes with the change in the temperature of the environment are called cold blooded animals.
Ex.: Fish , Frog etc.,
3. Flowering and non – flowering plants:
Ans: Flowering plants : The flowering plants bear flowers and fruits. Ex : Sunflower, Mango.
Non – flowering plants : The non flowering plants do not bear flowers. Ex : Mushroom, fern.
4. Algae and fungi :
Ans: Algae: These are aquatic plants which contain chlorophyll and can prepare their own food.
They may be unicellular and filamentous. Ex. Spirogyra
Fungi: These are non-green plants. They cannot prepare their own food. They are saprophytic.
Ex. Yeast
5. Annuals and Biennials:
Ans: Annuals : Plants which complete their life cycle in one year from seed to flower, fruits and
seeds and then die, are called annuals. Ex : Most herbs.
Biennials : Biennials are those plants which complete their life cycle in two years. In the first
year, these plants just grow. Flowers, fruits and seeds are produced in the second year.
6. Gymnosperms and angiosperms.
Ans: Gymnosperms: The plants that bear seeds but no fruits are called gymnosperms. Ex. – Cycas, Pinus
Angiosperms: The plants that bear seeds which are enclosed inside the fruits are called
angiosperms.
Ex. – Mango, Grapes, Apple etc.
7. Herbs and Shrubs:
Ans: Herbs : Herbs are small plants with a soft stem. They do not grow more than 3 to 4 feet in
height. Ex: Wheat, Paddy.
Shrubs : Shrubs are medium sized plants with hard and woody stems. Many branches are seen
arising just above the ground. Ex: Lemon, Hibiscus.
8. Parasites and saprophytes :
Ans. Parasites : Heterotrophs which obtain their food from other living organisms (without killing
them) are called parasites. Ex. Cuscuta, Viscum, Orobanche
Saprophytes : Heterotrophs which feed on the dead and decomposed bodies of plants and
animals are called saprophytes. Ex. Yeast, Mushroom.
9. Xerophytes and Hydrophytes:
Ans. Xerophytes : The plants living on land having scarcity of water, as in a desert are called
xerophytes. Ex. Cactus, Babool, Ber,
Hydrophytes : The plants which live in water are called hydrophytes.
Ex. Lotus, water lily, algae.
10. Shrubs and trees:
Ans. Shrubs : Shrubs are medium sized plants with hard and woody stems. Many branches are seen
arising just above the ground. Ex: Lemon, Hibiscus.
Trees : Trees are tall plants with hard and woody stems. They have a main trunk from which branches and leaves arise. Trees generally survive for a number of years.
Ex. Mango, Coconut, Neem.
CHAPTER – 3
SOIL
I. Define the following:
1. Soil – Soil is the uppermost layer of earth’s crust in which plants grow.
2. Weathering – The process of breaking down of parent rock material into fine soil particles by the action of various agents is called weathering
3. Soil erosion - The removal of top soil by wind, water or rain is called soil erosion.
4. Loam – Soils having mixture of different sized particles are called loam.
5. Soil texture – The way the soil feels when we touch, i.e, the nature and consistency of the soil is called soil texture.
6. Humus – Humus is the nonliving organic matter formed from the remains of the dead plants and animals by the activity of microorganisms present in the soil.
7. Terrace cropping – The growing of crops in steps cut into mountain slopes in the hills is called terrace cropping.
8. Residual soils – Residual soils are those in which the whole process of soil. formation, i.e., weathering and development of soil profile occurs at the same place.
II. Answer the following questions:
1. Which soil horizon is rich in humus?
Ans: A – horizon.
2. Which type of soil is best suited for growth of plants? Give reasons in support of your answer.
Ans: Loamy soil is the best suited for growth of plants. These soils :
(i) contain humus, providing fertility to the soil.
(ii) hold sufficient water due to the presence of smaller particles, and
(iii) contain enough air due to the presence of some large particles also.
3. What is meant by soil profile? Give the characteristics of different horizons observed in the soil profile.
Ans: Soil profile is the term used for the vertical section of soil to show the different layers or horizons of soil. Each profile has three main layers referred to as horizons.
1)A – horizon or top soil :
(i) It is the uppermost layer of soil which is darkest in colour.
(ii) It is rich in humus formed by the death and decay of plants and animals.
(iii) It is very fertile due to humus.
(iv) This layer is soft, porous and holds enough water.
(v) The roots of plants are present. In case of tall trees, the roots may grow down to the second horizon.
(vi) Living organisms like earthworms, insects, bacteria and fungi are present in this layer.
2) B – horizon or sub – soil :
(i) It is the next layer which is lighter in colour than the upper layer.
(ii) It is harder and more compact than A – horizon.
(iii) This layer is rich in soluble minerals and iron oxides.
(iv) Remains of plants and animals are not found in this layer.
(v) Roots of tall plants generally reach this layer.
(vi) Very little organic matter is found.
3) C – horizon :
(i) It is the lowest layer which is essentially the parent material represented by larger rock pieces.
Beneath the C - horizon is the bed rock itself. It can’t be easily dug up.
4. How is soil formed? Describe in brief.
Ans: The process by which soil formation takes place is called weathering. In the beginning large rocks were broken into smaller pieces by natural events like violent earthquakes. Then the process of weathering is carried further by many other agents. These are described below :
1. Temperature changes : Rocks expand when heated and contract when cooled. The hot sun causes the surface layer of rocks to expand more than the layers deeper down. These changes cause the rock surface to break apart.
2. Frost : Rain water may become trapped in small crevices of the parent rock. In winter, this water freezes to ice. The ice expands producing a lateral pressure, causing the crevices in the rocks to further open up.
3. Water : Continuous movement of rain and river water causes breaking down
of rock particles.
4. Wind : Minute rock particles are carried away by the blowing wind and gets
deposited elsewhere.
5. Living organisms : Weathering by living organisms is called biological
weathering. Certain life forms like the lichens can grow on the surface of rocks.
The lichens produce acids which corrode the rocky surface and produce fine
particles. In these fine particles, other organisms like microbes, insects and
worms grow and die. Thus more soil is formed. Roots further weather the
rocks and produce soil.
5. Name the different types of particles present in soil.
Ans: The different types of particles present in soil are gravel (stone), sand, silt and clay.
6. Describe the various types of soils and the basis of their classification.
Ans; A. On the basis of texture, the soil can be classified as sandy, silty, clayey or
loamy.
B. On the basis of soil colour, as black, red or laterite.
C. On the basis of place of soil formation, soils are classified into three types:
(i) Residual soils (ii) Transported soils (iii) Mountainous soils
(i) Residual soils : Residual soils are those in which the whole process of soil
formation occurs at the same place.
ii) Transported soils : Transported soils are those where the weathered soil particles are taken away to other places. Depending on the nature of these transporting agents, these soils may be
a) Alluvial, transported by running water
b) Eolian, by wind,
c) Glacial, by snow
d) Colluvial, by gravity
(iii) Mountainous soils : These are usually found in valley basins or on mountain slopes.
D. On the basis of chemical nature, soil may be acidic, alkaline or neutral.
7. Mention the characteristics of mountainous soil and black soil.
Ans: (1) Mountainous soils : (i) Soil consists of sandstones, clay, shales and limestones.(ii) Of all the soil types, humus content is maximum and so it is
very fertile.
(2) Black soil : (i) Rich in iron, magnesium and calcium derived from the basaltic rocks.
(ii) Soil is clayey, contains dead organic matter and water, ideal for growing cotton and sugar cane .
8. Distinguish between sandy, clayey and loamy soils.
Ans. (1) Sandy Soil : It is highly porous. Lot of air is present due to the presence of large particles. These soils however do not hold much water and lack humus. So it is not suitable for plant growth.
(2) Clayey Soil: Clayey soils have no or very little air between the particles, but hold enough water. These soils also contain some humus. So the soil is able to support plant growth.
(3) Loamy Soil : These are the best suited for plant growth. These soils:
(i) contain humus, providing fertility to the soil.
(ii) hold sufficient water due to the presence of smaller particles, and
(iii) contain enough air due to the presence of some large particles also.
9. Distinguish between residual and transported soils.
Ans. (i) Residual soils : Residual soils are those in which the whole process of soil formation occurs at the same place.
ii) Transported soils : Transported soils are those where the weathered soil particles are taken away to other places. Depending on the nature of these transporting agents, these soils may be
a) Alluvial, transported by running water
b) Eolian, by wind,
c) Glacial, by snow
d) Colluvial, by gravity
10. How is soil important to us? Explain.
Ans. Soil is valuable to man for food production. It is also a basic part of wild life habitats and recreational resources. Various soil organisms like earthworms, bacteria, insects and mammals use this as a natural habitat. Plants obtain water and minerals through this land resource. Plant sources of many medicinal drugs exist here. Wood, fibre, fruits, rubber, oils, dyes and various other economic products are all dependent on this land. So soil is important for our existence.
11. Describe the factors which cause soil erosion.
Ans. The factors that cause soil erosion are
i) Deforestation: Due to increasing population, forest is destroyed for agriculture, construction of buildings, roads, dams and industries. Due to deforestation , water does not seep down in the soil. Thus, soil particles are carried away by water. Since deforestation makes the land barren, wind erosion also takes place.
ii) Over – grazing: Over- grazing by large animal populations also destroys vegetation and results in barren lands. The barren lands do not hold water. So soil erosion occurs by strong winds.
iii) Poor farming methods: Ploughing loosens the soil and destroys its natural structure. Failure to replace humus after successive crops reduces the water holding capacity of the soil. The soil thus dries and is blown away by winds.
iv) Forest fires: Forest fires lead to soil erosion by wind and water.
12. How can soil erosion be prevented?
Ans. Soil erosion can be prevented by the following measures:
i) Deforestation should be stopped. Trees should be planted (afforestation). Trees and grasses hold the soil in place.
ii) To reduce the effect of strong winds in the fields, the boundaries of the fields should be planted with trees in two to three rows.
iii) To maintain the soil in its natural condition it is advisable to grow different crops. Crop rotation helps to maintain the fertility and water holding capacity of the soil.
iv) Proper drainage and irrigation arrangements should be made in the fields.
v) In hilly areas, terrace cropping should be practiced.
13. Describe the composition of soil.
Ans. The different components of soil are
i) Rock or soil particles of different sizes.
ii) Humus (organic matter)
iii)Soil water containing various inorganic salts.
iv) Soil air.
v) Soil organisms.
i) Soil Particles : The different types of particles present in soil are
Types of particles
Diameter
1. Gravel or stones
2. Sand
3. Silt
4. Clay
Above 2.0 mm
0.05 to 2.0 mm
0.005 to 0.05 mm
Below 0.005 mm
Gravel or stone has the largest particle size. Sandy soils are highly porous. Lot of air is present in sandy soils due to the presence of large particles. Clay soils have no or very little air in between the particles, but hold enough water.
ii) Humus : Humus is formed from the remains of the dead plants and animals by the activity of micro organisms present in soil. Humus increases the fertility of the soil.
iii) Soil water: Water held between the soil particles due to capillary action is called capillary water. This capillary water is available to the plant roots for absorption.
iv) Soil Air: Air is essential for the respiration of roots and soil organisms. Sandy soil has bigger air spaces than the other soils.
v) Soil organisms: A number of organisms like earthworms, bacteria, fungi, roundworms etc., are found in soil. Soil organisms are important because:
a) Earthworms burrow the soil, swallow it and make it loose and soft. b) Microorganisms cause the decomposition of dead plants and animals and
bring the minerals back to the soil. These minerals can again be used by
plants. Thus they help in the cycling of minerals.
c) Nitrogen fixing bacteria found in the root nodules of leguminous plants are
capable of absorbing the atmospheric nitrogen.
CHAPTER – 4
Fossils
Answer the following questions:
1. Define fossils.
A. Fossils are the remains of dead plants and animals which existed millions of years ago and got buried in the earth.
2. How are fossils formed?
A. A dead organism or its parts get buried under sediments of sand and other minerals. The sediments keep on depositing over a period of time. The soft parts decay but the hard ones survive and absorb minerals. These minerals gradually replace the hard parts of the organisms and convert them into hard stone, the fossil.
3. Mention the significance of the study of fossils.
A. Fossils tell us a lot about the living things which lived in the past, and how they changed. The earth’s surface consists of layers of rock. The fossils in each layer act as a record of the life that existed at that time.
4. What are fossils fuels?
A. The fuels which are formed from the remains of plants and animals which got buried millions of years ago are called fossil fuels.
5. Name three fossil fuels.
A. Coal, petroleum , natural gas.
6. Name the ultimate source of energy for fossil fuels.
A. Sun
7. Why are fossil fuels considered non- renewable sources of energy?
A. Fossil fuels are present in the earth in limited quantities, and very soon, these reserves will be exhausted. Because of their inability to regenerate fast enough, fossil fuels are termed non-renewable sources of energy.
8. Why should we not use fossil fuels?
A. Burning of fossil fuels releases CO2 in the air . This causes air pollution and thus harms the environment. So we should not use fossil fuels.
9. Write briefly about the following fossil fuels.
A. i) Coal: During Carboniferous period, large trees were present in abundance on the Earth. The trees on death got buried in the Earth. Very slowly, these trees got converted into peat, then lignite and finally coal.
ii) Petroleum: Petroleum is formed from the remains of living organisms (which got buried millions of years ago) in water. Petroleum is a complex mixture of solid, liquid and gaseous hydrocarbons mixed with salt water and earthly particles. Petroleum on refining gives petroleum gas, naphtha, petrol, diesel, kerosene, lubricating oil, wax and heavy oil.
iii) Natural gas : Natural gas was formed along with petroleum millions of years ago from the remains of living organisms which got buried under the Earth. Natural gas consists of 95% methane and the rest 5 % consists of ethane, propane and ethylene.
10. What is meant by energy crisis?
A. Energy needs of humans are increasing day by day because of its use to provide comforts of modern life. Increasing population, leading to growth of cities, and technological advancement has resulted in heavy demand on energy consumption. Because of increased demand and limited resources, imports of oil and petroleum products are increasing every year. The indiscriminate use of energy sources without developing proper alternative sources of energy is leading to an energy crisis.
Chapter – 5
Structure and Functions of Plant Parts
I. Define the following terms.
1. Tissues : The specialized cells which group together to perform a particular function are known as tissues.
2. Organs : Different tissues are grouped together into larger units called organs.
3. Venation: The arrangement of veins in the leaf blade is called
venation.
4. Gamete: The sex or reproductive cells produced from the
reproductive organs of male or female parent are called gametes
5. Pollination : Pollination is the transfer of pollen grains from the
ripe anther to the stigma.
6. Fertilization : The fusion of the male and female gametes is
called fertilization.
7. Zygote : The product of fusion of the male and female gametes
is called the zygote.
8. Fruit : A fruit is a ripened ovary formed after fertilization.
9. Seed : A seed is ripened ovule after fertilization.
II. Give the differences between the following:
1. Root and stem
Root Stem
1.It develops from radicle. 1. It develops from plumule.
2. Nodes and internodes are absent. 2. Nodes and internodes are present.
3. It is never green 3. It is often green
4. Leaves and buds are absent 4. It is bears leaves and buds.
5. It generally develops below the ground 5. It generally develops above the ground.
2. Node and Internode.
A. The place from where the branches and leaves arise on the stem is called the node. The portion of the stem between two nodes is called the internode.
3. Simple and Compound leaves.
A. The leaf with a single lamina is called a simple leaf. A simple leaf has an axillary bud.
Ex: Mango, Castor, China rose
The leaf in which the lamina is cut into a number of small leaflets on a common stalk is called a compound leaf. Leaflets do not bear axillary buds.
Ex: Rose, Neem, Tamarind.
4. Reticulate and Parallel venation.
A. When the veins in leaf lamina divide repeatedly forming a network, it is called reticulate venation. Dicot plants have reticulate venation.
Ex: Mango, Rose
When the veins run parallel to each other from the base to the tip of the lamina it is called parallel venation. Monocot plants have parallel venation.
Ex: Banana, Wheat, Grass.
5. Self pollination and Cross pollination.
Ans.
If the pollination takes place within the same flower or between flowers of the same plant, it is called self pollination.
If pollination takes place between flowers of different plants of
the same species, it is called cross pollination.
III. Answer the following questions.
1. Mention the two main systems found in plants.
A. Root system and Shoot system. The part of the plant body which fixes it to the soil is called the root system. The part of plant body above the soil is called the shoot system.
2. Describe the root systems found in plants. Give examples.
A. Tap root system and Fibrous root system are the two root systems found in plants.
Tap root system : Root system consisting of a single main root (called the tap root) from which lateral roots develop is called tap root system.
Ex. Neem, Mango
Fibrous root system: A number of roots of equal size arising in a cluster below the stem is called fibrous root system.
Ex: Wheat, maize.
3. What are the functions of roots?
A. i) Roots fix the plant to the soil.
ii) Roots absorb water and mineral salts from the soil which are then conducted upwards to the stem and leaves.
iii) Roots help in holding the soil together, thus , preventing soil
erosion.
iv) In some plants, roots are modified to perform additional
functions of storage, support or respiration.
4. Why certain plant parts are modified?
A. 1) Roots are modified for-
i) storage as in carrot, radish etc.,
ii) support as in banyan tree, sugarcane etc.,
iii) respiration as in mangrove plants.
2) Stems are modified for –
i) storage as in potato, onion, ginger etc.,
ii) photosynthesis as in cactus.
iii) support as in grape vine.
3) Leaves are modified-
i) as spines in xerophytes to prevent loss of water.
ii) as tendril for support .
iii) for trapping insects as in insectivorous plants.
5. a) Mention any two modifications found in roots. Give examples with diagrams.
Ans. i) Modification for storage: In plants like carrot, the roots instead of spreading in the soil become swollen. These swollen roots store food which we eat. Such roots are called tuberous roots.
ii) Modification for respiration: In certain plants which grow in saline marshy places, the root system produces vertically upwards growing branches above the soils. These roots help in respiration and are known as pneumatophores.
b) Name three plants having support roots.
Ans. Banyan tree, sugar cane, maize.
6. What are the main functions of the shoot?
A. 1) The stem bears the leaves, flowers and fruits. It serves as a link between the roots, the leaves and flowers.
2) The stem and its branches hold the leaves in such a manner that the leaves get maximum sunlight.
3) When young, it is green and manufactures food through the process of photosynthesis.
4) It carries water and mineral salts from the roots to the leaves and flowers.
5) It carries food manufactured in the leaves to roots and other parts of the plant body.
6) In some cases, the stems may be modified to perform the functions of storage, food- manufacture and support.
7. a) Which plant organs are modified for storage of food in a potato and onion?
Ans. Stem.
b) Name the stem modifications found in potato, ginger and onion.
Ans. Potato- tuber, ginger – rhizome, onion – bulb.
8. Name some modified roots and stems which are eaten by man.
Ans. Modified roots eaten by man – sweet potato, radish, carrot, beetroot.
Modified stems eaten by man – potato, onion, ginger.
9. Describe the modifications found in a cactus plant.
Ans. In cactus plant, the stem becomes fleshy and green. The stem prepares food and also stores water for long periods. The leaf is reduced to spines .
10. Why is the stem of a cactus plant thick and green? What is the role of spines?
Ans. The stem of cactus plant is thick and green to perform the process of photosynthesis and to store water for long periods. The leaf is reduced to spines to reduce the rate of transpiration.
11. Give one example of a plant with stem tendrils.
Ans. Grape vine
12. Name two insectivorous plants. Which part of the plant body is modified in these plants?
Ans. Pitcher plant and sundew plant are two insectivorous plants.
Leaf is modified in these plants.
13. Mention four functions of leaves.
Ans. 1)Leaves manufacture food for the plant body. The process of manufacturing food by the leaves is called photosynthesis. Leaves require water, carbon dioxide, sunlight and chlorophyll for making food.
2) The leaves on their surfaces carry tiny pores called stomata. Through stomata, plants take gases in and out during respiration and photosynthesis.
3) Plants give out extra amount of water in the plant through stomata in the form of vapours. This process is known as transpiration.
4) Leaves may be variably modified into spines or tendrils or modified to trap insects.
14. With the help of diagrams, describe the structure of a carpel.
Ans. Each carpel consists of a basal swollen part called the ovary. The ovary continues into a long style and ends in a knob-like part, called the stigma. The ovary contains many ovules. Female sex cell is present inside the ovule. Ovules and ovary finally develop into seeds and fruit respectively.
Refer figure 5.10 page no. 50 and 5.22 page no. 54.
15. Describe the different parts of a complete flower.
Ans. Each flower has a stalk called the pedicel. But some flowers do lack the pedicel, and such flowers are called sessile. Besides the stalk, a flower, in general, shows four sets of whorls or parts arranged as rings or whorls.
1. Calyx is the outermost whorl or set composed of green, leaf – like protective structures called sepals.
2. Corolla is the next inner whorl composed of brightly coloured petals. Being brightly coloured, petals attract insects for pollination.
3. Stamens are next to corolla and consist of anthers and filaments. Anthers are swollen structures present on the tip of filaments. The anthers produce a powdery substance consisting of tiny structures called the pollen grains. The stamens represent the male part of a flower. Male sex cells are produced inside the pollen grains.
4. The central part of the flower is the female part, consisting of a flask-shaped organ, called the carpel. Each carpel consist of basal swollen part called the ovary. The ovary continues into a long style and ends in stigma. The ovary contains many ovules. Female sex cell is present inside the ovule. Ovules and ovary finally develop into seeds and fruit respectively.
5. A flower consisting of all the four whorls – calyx, corolla, stamens and carpels – is called a complete flower.
Refer figure no. 5.21 page no. 54.
16. What part is played by stamens and carpels?
A. The stamens represent the male part of a flower.
The carpels represent the female part of a flower.
17. In which part of the flower is the ovule found?
A. Inside the ovary
18. Name the three agents of pollination.
A. Wind, water, insects.
19. Where does fertilization occur in a flowering plant?
A. Inside the ovule.
20 Describe the parts of a fruit. Draw a well-labelled diagram in support of your answer.
Ans. A fruit consists of two parts: i) The fruit wall (or pericarp), and ii) Seeds.
The fruit wall develops from the wall of the ovary. It may be thick or thin. It may be dry as in pea or gram or fleshy as in tomato and papaya. In fruits like mango, the pericarp is differentiated into three layers.
1. the outer layer called the epicarp,
2. the middle layer called the mesocarp and
3. the inner layer called the endocarp.
Refer figure 5.29 page no. 59
21. Outline the structure of a seed. Name its parts.
Ans. A seed consists of an embryo, one or two cotyledons and a protective seed coat. Embryo is represented by plumule and radicle. The cotyledons often contain the reserve food material for the developing plant. On germination , plumule gives rise to the shoot system while radicle gives rise to the root system.
Refer figure 5.30. page no. 60
Test yourself
1. Name the two main systems found in plants.
Ans. Root system and Shoot system.
2. Answer the following:
i) Name the two types of root systems found in plants.
A. Tap root system and fibrous root system.
ii) Give two examples each of plants where tap roots and fibrous roots are present.
A. Tap root – Mango, Neem
Fibrous root – grass, wheat.
iii) Name two examples of modified roots which you eat.
A. Carrot, Beetroot
iv) Name a plant in which supporting roots are present.
A. Banyan tree
v) Give two examples of plants with stem tendrils.
A. Grape vine, cucurbita
vi) Describe the modifications found in
A. a) Potato : Potato is a tuber. It is a small, thick and fleshy
structure. It has buds which are called ‘eyes’. It also has some scaly leaf-like structure . This swollen structure which stores food is called a tuber. New plants develop from the ‘eyes’ of the tuber.
b) Onion: Onion is a bulb. It is bulb like structure. The stem is short and bears small fibrous roots at the base and leaves above.
The outer leaves are dry and scaly. The outer dry leaves enclose thick fleshy leaves which store food. Buds are present in the leaf axils. New bulbs grow from the buds.
c) Cactus: In cactus plant, the stem becomes fleshy and green. The stem prepares food and also stores water for long periods. The leaf is reduced to spines to reduce the rate of transpiration.
3. Which imparts green colour to a leaf?
A. Chlorophyll
4. Name the following
i) A plant with no leaf – Dodder
ii) A plant with variegated leaf – Money plant
iii) A plant in which leaf is reduced to spines – Cactus iv) Two plants in which leaves are modified into tendrils – sweet pea, pea.
v) Three plants having reticulate venation in the leaves – Rose, Neem, Hibiscus.
vi) Three plants having parallel venation in the leaves – Paddy, grass, wheat.
5. Why is flower important to a plant?
A. Flower is the most important part of plant as it takes part in reproduction and leads to the formation of seeds and fruits. Seeds on germination produce new plants.
6. Name the different parts of a flower from outside to the center.
A. Calyx, Corolla, Androecium, Gynoecium
7. Name the parts of a stamen.
A. Filament, Anther.
8. Name the parts of a carpel.
A. Ovary, Style, Stigma.
Chapter – 6
HEALTH AND HYGIENE
I. Answer the following questions:
1) Define health.
Ans: Health: A state of complete physical, mental and social well –
being; without diseases is called health.
2) List four functions of food.
Ans: Food is required by the body for the following purposes:
i) For energy required to perform various functions to sustain life.
ii) For growth; Without proper food, body growth would not be possible.
iii) For repair of damaged or injured body parts. Repairs of damaged parts takes place by addition of new cells.
iv) For protection from diseases and infection.
3) Name the various nutrients in food.
Ans: Various nutrients in our food are
i) Carboydrates ii) Fats iii) Proteins
iv) Mineral salts v) Vitamins iv) Water.
In addition, roughage (fibre) is another important dietary constituent, which is required to prevent constipation.
4) Name the three groups of foods.
Ans: The three groups of foods are:
i) Energy – giving foods (like carbohydrates and fats)
ii) Body – building or growth – promoting foods (like proteins), and
iii) Protective foods (vitamins and minerals).
5) What are the two major factors responsible for the development of diseases?
Ans: i) imbalances in the diet, or due to
ii) infection by micro – organisms.
6) What is meant by a balanced diet?
Ans: Balanced Diet: A diet containing adequate amounts or proportions of proteins, Carbohydrates, fats, vitamins and minerals is called a balanced diet. In such a diet, energy – giving, body – building and protective foods are present in sufficient quantities.
7) Mention seven characteristics of good health.
Ans: A person is said to be healthy or having good health, if he / she
is
i) not suffering from diseases.
ii) Free from unnecessary anxiety.
iii) Free from social and physhological tensions.
iv) Free from mental problems.
v) Having good self confidence.
vi) Not handicapped physically.
vii) able to work efficiently.
8) What can be done to maintain good health?
Ans: i) Proper nutrition and balanced diet
ii) Proper food habits
iii) Personal and domestic hygiene
iv) Adequate physical exercise
v) Proper recreation, rest and sleep
vi) Clean food, water and air
vii) Keeping away from smoking, drugs and alcohol
viii) Timely vaccination
ix) Avoiding exposure to radiations
x) Proper health education.
9. Write, briefly about the following: i) Personal cleanliness
ii) Eye care iii) Oral hygiene iv) Clean water v) Clean air
vi) Clean food vii) Hygiene
Ans: (i) Personal cleanliness: Personal hygiene refers to the
cleanliness of one’s own body.
Following precautions need to be taken for maintaining personal hygiene:
i] Before and after taking meals, always wash your hands with
soap and water.
ii) Take bath regularly with clean water.
iii] Clothes, especially undergarments, should be changed daily
and wearing of very tight clothes must be avoided.
iv) Clean and regular toilet habits must be adopted for
maintaining good health.
v) The feet should be cleaned everyday and well protected.
(ii) Eye care: Suggestions concerning eye care are given below:
i) Eyes should be protected from bright sunlight.
ii) Television should not be watched continuously for long hours.
iii] Reading in dimlight, or while lying down should be avoided, as it puts
strain on the eyes.
iv] Eyes should be washed with plenty of clean and cold water.
v] Foods rich in vitamin A which is good for eye should be included in
the diet.
[iii] Oral Hygiene: Oral hygiene is mainly concerned with the care of teeth. The yellowing of teeth is due to a sticky film of saliva, food particles and bacteria, and is called plaque. Plaque and cavity formation are often caused by the consumption of sweets. Bacteria present in the plaque convert the sugar into an acid which dissolves away the enamel of the tooth. Ultimately a hole or cavity is formed in the tooth. Plaque formation and other diseases can be avoided by
i] not eating foods like sweets, chocolates and ice – creams
ii] consuming foods such as raw vegetables, carrots, spinach (palak),
radish, cabbage and fresh fruits (the teeth and gums get good exercise
when fibrous foods are eaten),
iii] brushing teeth thoroughly and regularly everyday in the morning and
again before going to bed, and
iv] using fluoride toothpaste.
[iv] Clean water: Provision of safe drinking water is a necessary requirement for maintaining the health of both the individual as well as the community.
[v] Clean air: i) There should be proper ventilation in the house.
ii) Planting of trees purifies air.
[vi] Clean food: Food should be kept covered. Wash the fruits and vegetables before eating.
[vii] Hygiene: Hygiene is defined as the science of health and the prevention of diseases.
10. What are communicable diseases? Give five examples.
Ans: Communicable diseases are the diseases that spread from one person to another by means of air, water, food or physical contact with diseased person and insects.
Examples: Malaria, cholera, tuberculosis, AIDS, and cough.
11. How are communicable diseases spread? List four agents.
Ans: Communicable diseases may be transmitted from infected person to
healthy person in different ways:
i] Direct contact: Infection may be transmitted by direct contact from
skin to skin e.g., leprosy, skin and eye infections, AIDS.
ii] Droplet infection: Spread by direct spray of droplets of saliva during
coughing, sneezing, speaking and spitting, e.g., whooping cough,
tuberculosis, diphtheria, common cold.
iii] Contact with soil: For example, hookworm larvae, tetanus, mycosis.
iv] Though contaminated food and water, as in cholera and typhoid.
12. What is the aim of chlorinating water?
Ans: Chlorinating destroys the micro – organisms present in water.
13. How does pollution affect our health?
Ans: Air pollution causes diseases like asthma, bronchitis and irritation in the eyes and throat.
Similarly, water pollution makes water unfit for drinking. Polluted water causes serious water – borne diseases like cholera, typhoid, dysentery and jaundice. Sound pollution causes head ache, deafness etc.,
14. What first aid steps would you take for.
i) Cuts, ii] Bruises, and ii] Burns?
Ans: i) Cuts: i) Expose the cut, removing whatever clothing may be
there.
ii] Wash the cut with soapy water and then hold it under
cold running water. Make sure that all dirt or other
undesirable material is removed. Use a cotton swab if
necessary.
iii] Dry the cut with sterile gauze.
iv] Apply mild tincture of iodine all over the cut and the
surrounding skin.
v] After the blood flow stops, lower the cut with a clean,
dry, soft and absorbent dressing.
vi] Raise the cut area above the level of the heart, if
possible.
vii] Do not disturb the clot of blood formed over the cut.
ii) Bruises: For treating a bruise, a cold pack or an ice pack is required. Cover the bruise with a cold pack or an ice pack for a few hours. This reduces pain and swelling.
iii) Burns: i) When someone’s hair catches fire, put the fire off with water, if available. Otherwise smother the flames with a thick towel or blanket. Do not let the victim run.
ii) If you catch fire, wrap yourself in a blanket or coat, or roll on the floor or the ground.
Remove clothing that has been soaked in hot oil or boiling water immediately. Do not remove dry, burned clothing or any clothing that is sticking to a burn.
Remove all rings or bracelets that could impede circulation to or away from the burned tissue.
Do not apply ointment, such as petroleum jelly or butter to a burn. Do not cover with cotton that will stick to the burn. Gently wash it with a mild soap and rinse it with water thoroughly. Keep burn area elevated above the level of the heart.
Leave the burnt area uncovered unless it is likely to get dirty or cause pain when it rubs against clothing. In that case, put a light sterile bandage over the burnt area. Change the dressing daily.
Do not pop the blisters. Burn blisters will burst on their own in a few days. Remove the dead skin with a clean cloth and soap.
iii) If you burn your tongue with a hot drink or food take few grains of sugar. Ice cold water can also be used.
iv] Avoid exposing burnt areas to the sun.
Biology (I.C.S.E) Unit – I
Life on Earth
Characteristics of the Living
I. Study Questions.
1. b 2. a 3. c 4. b 5. b
II.
1. Biology 2. Cell 3. Unicellular 4. Cells
5. Oxygen, Carbondioxide. 6. Sea anemone
IV. True/ False
1. False
2. True
3. False
VI.
1. Hen’s egg,
2. A car doesn’t grow, reproduce and respond to stimuli. It does not have any cellular organisation.
3. Non- green plant – mushroom. An animal which does not move about is sea anemone.
4. Microscopic plant- Pencillium, Microscopic animal- Amoeba.
5. All living organisms need food to get energy so that they can do various activities. Food also help in body growth as well as maintenance and repair.
6. Stomata
Test Yourself Page No. 8
1. Yes. There are certain common features between living and non- living things. They are
i) Both possess mass, shape and occupy space.
ii) Both have a structural unit – cells in the living and molecules in the non – living things.
Ans. 2. Table 1. 2 page no. 7
Ans. 4. i) Response : A response is an activity in the living body that results from
a stimulus.
ii) Stimulus :- Anything which produces a response in an organism is called stimulus.
iii) Phototropic : Movement of the shoot system towards sun light.
iv) Geotropic: Movement of the root system downwards in the soil.
Ans. 3. Life Cycle : Living things start their life from a single cell. In case of animals life cycle starts from birth ® growth ® reproduction ® death. In plants life cycle begins from seeds or spores.
Life span : The period during which the life cycle is completed is called the life span.
5. i) Urine, sweat, carbon dioxide.
ii) Carbon dioxide, water vapour.
Test- Yourself page no 10
Ans.
1. Microscope
2. Bacteria virus, Amoeba
3. Table 1.3 page no. 9.
4.
Plant Cell Animal Cell
1. Possess a rigid cell well. 1. Cell wall is absent
2. Chloroplasts are present 2. Chloroplasts are absent
5. Euglena
Extra Fill ups:
6. Aristotle is known as father of Biology.
1. Hydra and sea anemone use tentacles for obtaining food.
2. Botany deals with the study of plants.
3. Zoology deals with the study of animals.
4. Biology deals with the study of living things.
Chapter-7
Our Environment
I. Give differences between the following:
1. Environment and surroundings.
Ans: The term environment is used to denote all living and non – living things. In other words, the living organisms and their surroundings constitute the environment.
2. Food chain and Food Web.
Ans: FOOD CHAIN Process of eating and being eaten; a chain showing what
animals eat.
FOOD Web Network of a number of interconnected food chains is called food
web.
3. Producers and Consumers.
Ans: Green plants which manufacture food, are called producers. Both herbivores and carnivores are called consumers, as these cannot manufacture their own food and consume plants or animals, as their food source.
4. Herbivores and Carnivores.
Ans: Animals which feed directly on plants like cow and goat, are called herbivores or plant eaters. Animals which eat herbivores, such as lion. are called carnivores or animal eaters.
5. Decomposers and Scavengers
Ans: Decomposers: Living organisms which derive their food from the dead and decaying plants and animals are called decomposers.
Scavengers: Animals that feed on dead flesh are called scavengers. Examples : Hawk, crows, jackals, vultures.
II. Define the following terms:
Ecology: Ecology is a branch of Biology which deals with the interaction between the living and the non – living environment.
Ecosystem: The plants and animals together with the non – living environment in a given habitat, form an ecosystem.
Environmental factors: Temperature, light, water, air (oxygen and carbon dioxide), rocks, soil etc are called environmental factors.
Energy flow: In a food chain, transfer of energy takes place from one organism to another in the form of food transfer from producers to herbivores to carnivores. This is called energy pathways or energy flow.
Scavengers: Animals that feed on dead flesh are called scavengers. Examples : Hawk, crow, jackals, vultures.
Population: A population is the total number of individuals (of plants or animals) of the same kind living in one area.
Community: A community is all the plants and animals that live together in one area or habitat.
Food chain: Process of eating and being eaten: a chain showing what animals eat.
III. Answer the following questions:
1. Name the different kinds of living organisms which exist in our environment.
Ans: Plants and animals including human beings (producers, consumers and decomposers).
2. How are the following adapted to live in their respective environment?
Ans: (i) A cactus plant: The stem in these plants has become spongy, so as to store water. Leaves have been reduced to spines in order to reduce loss of water from the plant’s surface. The function of the leaf has been taken over by the stem which has become green.
(ii) Camel: (i) It is capable of adjusting its body temperature to that of the surrounding desert habitat and there by the water loss by perspiration and other means is drastically minimised. (ii) Camel can live without food or water at a stretch for as many as 10 days. When there is no water available to drink, it passes about half a litre of urine which is 10 – 20 times less than what it passes when water is available. (iii) When water is available, the animal can drink about 3 buckets of water (50 litres) at one time.
(iii) Water lily: A waxy waterproof coating is present on the leaves of water lily which prevents their decay in water.
(iv) Hydrilla: The leaves in Hydrilla are long and thin so that the strong water currents are not able to tear them apart.
(v) Palms: In palm tree the leaves become deeply incised or serrated to reduce the effect of wind.
3. Name two biodegradable materials.
Ans: (i) Vegetables (ii) Fruits.
4. Name one non – biodegradable material
Ans: Plastic
5. Name two scavengers
Ans: (i) Vulture (ii) Hawk
6. Name the raw materials used by plants to manufacture their food
Ans: Water, carbon dioxide, sun light, chlorophyll.
7. Which gas is released during the process of photosynthesis?
Ans: Oxygen
8. How have the socio – cultural activities influenced environment?
Ans: Socio – cultural environment has adversely affected the quality of our environment. We do not have clean air to breathe, safe and clean water to drink. Instead, we have congested roads, a highly polluted atmosphere and a large number of tall buildings and industries to cope with the increasing population.
9. Write on the cultural component of the environment.
Ans: Cultural component consists of the human influences on the environment. Man’s ever-increasing numbers and his greed to possess more and more physical comforts of life has greatly modified the natural environment. This modified natural environment or man-made environment is also termed socio-cultural environment.
10. Write in brief about the biotic components of the environment.
Ans: The living component consists of plants and animals including humans. Green plants which manufacture food, are called producers. Animals feed on plants directly or indirectly. Animals which feed directly on plants like cow and goat, are called herbivores or plant eaters. Animals which eat herbivore, such as lion are called carnivores or animal eaters. Both herbivores and carnivores are called consumers, as these cannot manufacture their own food and consume plants or animals, as their food source.
The micro organisms which derive their food from the dead and decaying plants and animals are called decomposers. Decomposers are important in the cycling of nutrients or minerals in nature. Bacteria and fungi act as decomposers.
Scavengers: Animals that feed on dead flesh are called scavengers.
11. Write in brief about the abiotic components of the environment.
Ans: Temperature, light, water, air, rocks, soil etc. are called abiotic components of the environment.
1. Temperature: The temperature is measured by a device called thermometer. Most plants and animals grow well in warm places, but some need a cold climate. Plants and animals show adaptations to live in their particular climate.
2. Light: Green plants need light to make food and to grow. Animals such as earthworms, centipedes, millipedes do not like light. They move away from light. The ultimate source of light and energy is the Sun.
3. Water: All living organisms need water for their sustenance. Water covers 4/5th of the earth’s surface. It makes up 60-70 percent of our body weight. Water is required for growing crops, in industry and for human existence.
4. Air: animals and plants require oxygen to stay alive. Plants, in addition to oxygen, also require carbon dioxide to make food. Carbon dioxide concentration in the atmosphere is going up, leading to an increase in temperature and thus warming of earth (global warming). Wind plays an important role in the dispersal of seeds and fruits.
5. Soil: Without soil, most of the plants would not exist. And in the absence of plants, other forms of life would not exist. The best soil for growing plants is one which is a mixture of clay, silt and sand. Such a soil is called is called loam soil.
12. Give examples of three food chains operating in nature?
Ans: (i) Grass ® Insects ® Birds
(ii) Algae ® Insects ® Small fish ® Large fish
(iii) Grass ® Insects ® Frog ® Snake ® Eagle
13. Why are plants called producers?
Ans: Plants are called producers as they prepare their own food.
14. What is meant by a food web? Explain with the help of a simple diagram.
Ans: Food web is a network of a number of interconnected food chains. Diagram Page No.87 Fig.1.10.
15. What would happen if any of the links is missing in the food chain?
Ans: If any one of the links is missing in the food chain, it will lead to the death of other animals. For Eg: grass Deer Lion. If deer is missing, lion won’t get food as they cannot eat grass and they will also die. If lion is missing deers will eat away all the grass without leaving any grass and finally they will also die because of starvation.
16. “Life would be impossible without plants.” Explain.
Ans: Animals depend upon plants in various ways.
1. For Food – All animals depend for their food, directly or indirectly, on green plants.
2. For Oxygen – Plants give out oxygen during the process of photosynthesis. This oxygen, is used by animals and plants for their respiration.
3. for shelter – Some animals depend on plants for shelter. If plants are not there animals won’t be able to breathe and they won’t get food. Animals also will die.
17. Explain the importance of recycling in the environment.
Ans: When the plants and animals die, their dead bodies are acted upon by decomposers (micro organisms). Decomposers convert the dead bodies into simple compounds which enter the soil. These simpler compounds can be used by plants again. Thus recycling makes the nutrients available to the plants for their growth. Plants are eaten by animals directly or indirectly. Thus these nutrients reaches the body of animals.
18. Mention the role played by the decomposers in an ecosystem.
Ans: Decomposers are important in the cycling of nutrients or minerals in nature. Minute living organisms (called micro – organisms) such as bacteria and fungi act as decomposers. These micro – organisms convert the dead bodies into simpler compounds like CO, N, H O, H S etc. Which enter the soil or are released into the atmosphere. These simpler compounds can then be used again by the plants. This is how minerals are recycled in nature.
19. Justify the statement, “No living organism can live by itself”.
Ans: All living things depend on other living things, directly or indirectly. For instance, a deer needs grass to live, and a lion needs deer to live. In this example, a deer is directly dependent on grass, and the lion’s dependence on grass is indirect. In a similar manner, all the plants, birds, reptiles, fish, insects, etc., are connected to each other, and depend, directly or indirectly, on each other. From this it is clear that no living organism can live by itself.
20. Name three pollutants each of air, water and soil.
Ans: Pollutants of air:- Harmful gases, smoke, dust.
Pollutants of water:- Sewage, industrial wastes, oil spill
Pollutants of soil:- Garbage, fertilizers, pesticides, plastic.
Test yourself
1. Answer the following questions:
(i) Name any four conditions which make life possible on the earth.
Ans: Presence of oxygen, presence of water, presence of atmosphere and right distance of the earth from the Sun are the four conditions that make life possible on the Earth.
(ii) Why is the Earth called a unique planet in the Solar system?
Ans: Moderate temperature, right distance of the Earth from the Sun, right amount of mass and gravity, presence of oxygen, water and atmosphere etc. make the Earth a unique planet in the solar system.
(iii) Into how many spheres is the planet Earth divided? Write a brief note on each
layer of the Earth.
Ans: The planet Earth is also called as geosphere. It consists of three spheres – (i) Lithosphere, (ii) Hydrosphere and (iii) Atmosphere. The outer rocky part around the Earth is called Lithosphere. The depressions in the lithosphere are filled with vast oceans and is called the hydrosphere . The envelope of air surrounding the lithosphere is called atmosphere. Inside of the Earth (geosphere) is also made of layers. At the centre is a solid inner core made up of iron and nickel. Surrounding the inner core is the outer core which is liquid in nature and which is mostly made up of iron, nickel and sulphur. Surrounding the outer core is the mantle. It is made up of molten magma. The outer rocky layer of Earth is called the crust.
(iv) What is atmosphere? Give its composition. Also state uses of two major components of air.
Ans: The envelope of air surrounding the Earth is known as atmosphere.
Composition of the Atmosphere: The atmosphere contains a mixture of the following gases: (i) Nitrogen-78% (approx.) (ii) Oxygen 21% (approx.) (iii) Carbon dioxide (0.03% to 0.04%) (iv) Noble gases-0.09% and (v) Water vapour (approx. 4% of the total volume of air). Besides the above gases, the lower layers contain sulphur dioxide gas, carbon, dust particles, salts and pollen grains, etc.
Uses: (i) Oxygen: it is used for breathing by animals and plants. It helps in burning.
(ii) Nitrogen: In the elemental form nitrogen is absorbed by N2 fixing bacteria which increases the fertility of soil.
(v) State three benefits of the atmosphere.
Ans: (1) It acts as a protective blanket for the Earth. It absorbs most of the harmful radiations such as ultraviolet radiations and X-rays coming from the sun. (2) It is a source of oxygen, which is required for respiration by all the plants and animals. (3) It provides oxygen for burning the fuels for various domestic or industrial purposes.
2. Define the following terms.
(i) Biosphere.
Ans: The part of the Earth where plants and animals exist is called the biosphere.
(ii) Environment.
Ans: The living organisms and their surrounding constitute the environment.
(iii) Habitat.
Ans: The place where the organisms live is called the habitat.
(iv) Natural Environment.
Ans: Both biotic and abiotic components together constitute the natural environment.
3. Name the primary source of energy in the environment.
Ans: Sun
4. Name the three components of the environment.
Ans: Biotic, abiotic and cultural components.
5. Name three abiotic factors of the environment.
Ans: Temperature, air and soil.
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