Chapter 4 – (b) Survival Strategies : Adaptation | Life Science Solution Class 10

Book Name	: Life Science And Environment
Subject	: Life Science
Class	: 10 (Madhyamik)
Publisher	: Calcutta Book House (P) Ltd
Unit Name	: Evolution And Adaptation

Objective-type questions (MCQ)

Question 1

Answer

Habitat.

Question 2

1. Evolution
2. Adaptation
3. Mutation
4. Modification.

Answer

Adaptation.

Question 3

1. Adaptation
2. Evolution
3. Both simultaneously
4. Mutation

Answer

Adaptation

Explanation:

Adaptation is the first response of organisms to changing environmental conditions. Evolution occurs over long periods of time through genetic changes in a population, and is a gradual process that results in the emergence of new species. Therefore, adaptation comes first and is a part of the process of evolution.

Question 4

Answer

gills

Explanation:

The respiratory organ of rohu fish is gills.

Question 5

1. Three
2. Five
3. Three pairs
4. Seven.

Answer

three

Explanation:

Rohu fish has three pairs of fins – pectoral, pelvic, dorsal, anal and caudal fins.

Question 6

Which fins are paired in rohu fish ?-

1. Dorsal fin
2. Anal fin
3. Anal and tail fins
4. Pectoral and pelvic fins.

Answer

Pectoral and pelvic fins

Explanation:

Pectoral and pelvic fins are paired in rohu fish.

Question 7

1. Air bladder
2. Skin
3. Scales
4. Lateral line.

Answer

lateral line

Explanation:

The lateral line is the organ that helps rohu fish to feel pressure, depth of water, and temperature.

Question 8

Which organ is responsible for maintaining buoyancy of rohu fish ?-

1. Swim bladder
2. Fins 
3. Air sacs
4. Myotome muscle.

Answer

Swim bladder.

Question 9

1. Whale
2. Kol (Anabas)
3. Rohu fish
4. Magur (Clarias)

AnsweR

Rohu fish.

Question 10

1. Air bladder
2. Air sacs
3. Lungs
4. Accessory respiratory organ.

Answer

lungs

Explanation:

The main breathing organ of pigeon is lungs.

Question 11

Answer

Both fish and bird

Explanation:

Both fish and bird show double respiration. Fishes use gills for respiration, and oxygen is extracted from water. Birds use lungs for respiration, and during inhalation, air passes through the lungs and then into the air sacs. During exhalation, air passes from the air sacs through the lungs and then out of the body. This allows for a continuous flow of oxygen-rich air and maximizes oxygen uptake.

Question 12

1. Pigeon
2. Rohu fish
3. Shark
4. Whale.

Answer

pigeon

Explanation:

Air sacs are found in the respiratory system of birds, including pigeons. These air sacs play an important role in bird respiration by allowing the flow of air in one direction, ensuring that fresh oxygen is constantly available to the bird’s respiratory system. Additionally, air sacs help to cool the bird’s body during flight and aid in vocalization.

Question 13

1. Five
2. Nine
3. Eight
4. Ten.

Answer

nine

Explanation:

Pigeons have nine air sacs in their respiratory system, which play an important role in their breathing process. The air sacs act as a bellows, helping to move air through the respiratory system and into the lungs, where gas exchange occurs.

Question 14

Answer

Xerophytes

Explanation:

Cactus belongs to xerophytes, which are plants adapted to survive in arid or desert environments with little water availability. They have evolved various structural and physiological adaptations to reduce water loss and store water efficiently, such as succulent stems and leaves, reduced or modified leaves, and deep roots to access underground water.

Question 15

1. Root
2. Leaf
3. Stem
4. Flower.

Answer

stem

Explanation:

The phylloclade of cactus is the fleshy stem-like structure which is formed by the modification of the stem.

Question 16

1. Photosynthesis
2. Transpiration
3. Respiration
4. Metabolism.

Answer

Transpiration

Explanation:

Spines are the modified structure of the leaf to check transpiration by reducing the surface area of the leaf to minimize water loss and protect the plant from herbivores.

Question 17

Which part of the cactus mainly performs photosynthesis ?-

1. Root
2. Stem
3. Spine
4. Root and Stem.

Answer

Stem

Explanation:

The stem of the cactus mainly performs photosynthesis. The stem is green and flattened, which allows it to absorb sunlight and carry out photosynthesis. In addition to the stem, some species of cactus also have photosynthetic tissue in their leaves or phylloclades.

Question 18

Leaves of cactus get modified into-

1. Spines
2. Thorns
3. Tendrils
4. Spines and tendrils.

Answer

spines.

Explanation:

The leaves of cactus get modified into spines. This is an adaptation to reduce water loss from the plant. Since the cactus grows in dry and arid regions, it needs to conserve water to survive. The spines also act as a deterrent to prevent animals from eating the plant.

Question 19

1. Silty soil
2. Sandy soil 
3. Saline soil
4. Clayey soil.

Answer

clayey soil

Explanation:

Sundari plants grow in clayey soil, which is found in the deltaic region of the rivers. Sundari trees are commonly found in the Sundarbans, which is a mangrove forest delta located in the Bay of Bengal. The clayey soil of this region is rich in nutrients and organic matter, which makes it ideal for the growth of these plants.

Question 20

1. Xerophytes
2. Hydrophytes
3. Halophytes
4. Epiphytes.

Answer

hydrophytes

Explanation:

Sundari is a species of mangrove tree and it belongs to the group of hydrophytes, which are plants that can grow in water or in very wet soil. These plants have evolved special adaptations to live in these conditions, such as the ability to tolerate salt and aerenchyma tissue for gas exchange.

Question 21

1. No water
2. Large amount of general soil water
3. Large amount of salty water
4. Small amount of water in soil.

Answer

Small amount of water in soil.

Explanation:

Physiologically dry soil is soil that has very low water content, making it difficult for plants to absorb water and nutrients. It is different from soil that is completely dry, as there may still be some moisture present but not enough to support plant growth. In physiologically dry soil, there is a small amount of water present in the soil, but it may be difficult for plants to access due to low water potential.

Fill in the blanks

Question

1. Adaptation that occurs due to living in new habitat is called ____ adaptation.
2. Adaptation that occurs due to living in old habitat is called ____ adaptation
3. Adaptation is the cause of ____.
4. To experience less resistance during swimming the body of fishes become ____ shaped.
5. The V-shaped muscles of fishes are known as ____ muscles.
6.  ____ ____ is known as hydrostatic organ of fishes.
7. Rohu is an ____ animal.
8. Gills are an adaptive character of ____ animal.
9. Modification of ____ limbs form wings.
10. Presence of feathers is the characteristic adaptive feature of ____.
11. The respiratory organs of bird are provided with ____ ____.
12. As Lotus lives in water, thus it is ____.
13. Transpiration rate of Lotus is ____.
14. Large number of air cavities are present in ____ of the Lotus.
15. As major part of Lotus plant remains submerged, the transpiration rate is ____.
16. Cactus belong to ____ because they grow in habitat.
17. In Opuntia the stem becomes flat, fleshy, green and is called ____.
18. Leaves of Opuntia is modified into ____.
19. Leaves are modified into spines to check  ____.
20. Stomata in the leaf of cactus is present in ____ epidermis.
21. Sundari plant generally grows in ____ soil
22. Sundari plant is ____ because it grows in saline soil.
23. Example of a mangrove species is ____.
24. In Sundari leaves stomata are restricted to the ____ epidermis.
25. Which one is the adaptive feature of Opuntia ____.
26. Vegetation in a saline habitat is called ____ vegetation. 
27. Which feature is not present in Heritiera ____. 
28. Halophytic adaptation is found in ____. 
29. Phylloclade is the modification of ____ for xerophytic adaptation. 
30. Gills are an adaptative character of ____. 
31. Fish can swim at different levels in water with the help of ____.
32. Lung is provided with ____ in pigeon. 

Answer

1. Habitat
2. Homeostatic
3. Evolution
4. streamlined
5. Myotome
6. Swim bladder
7. Aquatic
8. Aquatic
9. Forelimbs
10. Birds
11. Air sacs
12. Hydrophyte
13. Low
14. Parenchyma
15. Low
16. Xerophytes
17. Cladode
18. Spines
19. Transpiration
20. Both upper and lower
21. Saline
22. Halophyte
23. Sundari
24. Lower
25. Spines
26. Halophytic
27. Secondary growth
28. Mangroves
29. Stem
30. Aquatic
31. Swim bladder
32. Air sacs

Very Short Answer (VSA) type questions

Question 1

Mention one example each from aquatic plant and aquatic animal. 

Answer

Question 2

Answer

Rohu fish, its adaptive feature is the presence of gills for respiration underwater.

Question 3

Name an animal having secondary aquatic adaptation. Name the adaptive feature. 

Answer

Hippopotamus is an animal having secondary aquatic adaptation and its adaptive features are webbed toes, nostrils and ears that can be closed underwater, and a streamlined body for efficient swimming.

Question 4

What is locomotory organ of fish? 

Answer

The locomotory organ of fish is the paired fins and the unpaired fins.

Question 5

Name a fish which does not contain swim bladder. 

Question 6

Name two fishes in which additional breathing organ is present. Or, Name two animals which possess accessory respiratory organs. 

Answer

Pangolin and Anaconda are two animals which possess accessory respiratory organs.

Question 7

Name the organ of flight in bird. 

Answer

The wings are the organs of flight in birds.

Question 8

Mention the number of air sacs present in pigeon. 

Answer

Pigeons have a total of nine air sacs.

Question 9

What is the name of wing feathers? 

Answer

The name of wing feathers in birds is “remiges”.

Question 10

What are rectrices? 

Answer

Rectrices are the large, stiff feathers that form the tail of a bird.

Question 11

Answer

Lotus leaves have a waxy covering to repel water and prevent waterlogging as they grow in an aquatic environment.

Question 12

What are xerophytes? 

Answer

Xerophytes are plants that are adapted to survive in environments with little water, such as deserts or arid regions.

Question 13

What is it called when the stem is modified to function as leaf? 

Answer

It is called phylloclade.

Question 14

Why the leaves of cactus are modified into spine ? Or, Mention one importance of modification of leaf into spine in cactus. 

Answer

The leaves of cactus are modified into spines to reduce the surface area of the plant exposed to the sun and hence minimize water loss through transpiration.

Question 15

Why is the epidermis of Phanimanasa covered with thick cuticle? 

Answer

The epidermis of Phanimanasa is covered with a thick cuticle to reduce water loss and protect the plant from desiccation as it lives in arid regions.

Question 16

Why is the stem of phanimanasa flat and green ? 

Answer

The stem of Phanimanasa is flat and green because it is modified to carry out photosynthesis as an adaptation to living in a dry habitat with limited water availability.

Question 17

What is phylloclade? Give an example. 

Answer

A phylloclade is a modified stem that resembles a leaf or a flattened stem that takes over the functions of photosynthesis and water storage. An example of a plant with phylloclades is the Opuntia cactus.

Question 18

What kind of structure are the spines of cactus? 

Answer

The spines of cactus are modified leaves.

Question 19

What are halophytes? 

Answer

Halophytes are plants that are adapted to grow in saline (salty) soils or waters, such as coastal salt marshes, estuaries, and mudflats.

Question 20

Name the vegetation found in the soil which contains excess salt in water.

Answer

Halophytic vegetation.

Short Answer (SA) type questions

Question 1

What is adaptation?

Answer

Adaptation is the process by which organisms change their physical or behavioural characteristics to become better suited to their environment and increase their chances of survival and reproduction.

Question 2

Answer

Primary adaptation refers to the adaptations developed by an organism to live in a particular habitat from the beginning of its evolution. For example, the adaptations of aquatic animals like fish to live and respire underwater.

Question 3

What is secondary adaptation?

Answer

Secondary adaptation refers to the adaptation that occurs due to changing environmental conditions such as migration to a new habitat. It involves modifications in an organism’s structure, function, or behaviour that enhance their survival and reproduction in the new environment.

Question 4

What is the aim of adaptation?

Answer

Adaptation aims to:

• Enhance Survival: Adjust traits for better survival in changing environments.
• Ensure Reproduction: Improve chances of successful reproduction and passing on genes.
• Optimize Function: Tailor traits to perform effectively within specific ecological niches.
• Increase Fitness: Maximize overall reproductive success to thrive in the long term.

Question 5

What is double adaptation ? Give a suitable example.

Answer

Question 6

What is convergent adaptation?

Answer

Convergent adaptation is the process by which unrelated organisms evolve similar adaptations due to living in similar environments or performing similar functions. This is also called convergent evolution.

Question 7

What is divergent adaptation?

Answer

Divergent adaptation is the process by which species evolve different adaptations to similar environmental conditions or niches, resulting in the development of distinct traits and characteristics over time. This can lead to the formation of different species from a common ancestor.

Question 8

Which fish does not possess air bladder?

Answer

The cartilaginous fish such as sharks and rays do not possess swim bladder.

Question 9

What do you mean by hydrostatic organs?

Answer

Hydrostatic organs are specialized structures in animals, such as the swim bladder in fishes, that help them to maintain buoyancy and adjust their depth in water without using much energy. These organs work by changing the volume of gas or liquid inside them, thus increasing or decreasing the animal’s overall density.

Question 10

How many air sacs are present in pigeon?

Answer

Pigeons have nine air sacs in their respiratory system, which are connected to the lungs and allow for efficient gas exchange during flight. The air sacs also play a role in thermoregulation, vocalization, and buoyancy control.

Question 11

Answer

Xerophytes are plants that have adapted to survive in dry or arid environments with little water. They possess several adaptations such as reduced leaves, thick cuticles, deep roots, and water-storing tissues to help them conserve water and tolerate high temperatures.

Question 12

What are halophytes?

Answer

Halophytes are plants that are adapted to grow in saline soils or saltwater, such as coastal areas or salt flats. They have specialized mechanisms to tolerate high levels of salt in the soil or water, such as salt excretion or salt storage in leaves. Examples of halophytes include mangroves, saltbushes, and seagrasses.

Question 13

What are mesophytes?

Answer

Mesophytes are plants that are adapted to grow in environments with moderate availability of water, neither too dry nor too wet. They grow in habitats such as forests, grasslands, and agricultural lands where there is adequate water supply. Mesophytes do not have any special adaptations for water conservation, unlike xerophytes or halophytes.

Question 14

What are the xerophytic organisms?

Answer

Xerophytic organisms are plants that are adapted to survive in dry or arid environments with very little water availability. Examples include cactus, agave, yucca, and succulents.

Question 15

What is phylloclade ?

Answer

Phylloclade is a flattened, leaf-like stem modification in some xerophytic plants such as cactus and euphorbias, which performs the functions of photosynthesis, food storage, and water storage.

Question 16

Answer

In Opuntia stem, the following modifications take place to check transpiration:

1. The stem becomes flattened, which increases the surface area to volume ratio and reduces water loss due to transpiration.
2. The stem becomes fleshy, which helps in the storage of water and makes the plant more resistant to drought.

Question 17

Why is the stem of Opuntia flat?

Answer

The stem of Opuntia is flat to reduce the surface area and limit water loss through transpiration.

Question 18

What is the utility of the transformation of leaves of phylloclade into spiny structure?

Answer

The transformation of leaves into spines helps to protect the plant from herbivores and also reduces water loss through transpiration.

Question 19

In which plant is phylloclade seen? What is its adaptive role in that plant?

Answer

Phylloclade is seen in the cactus. Its adaptive role is to reduce the surface area for transpiration, to store water, and to carry out photosynthesis.

Question 20

What do you know about mangrove vegetation and mangrove plants?

Answer

Mangrove vegetation refers to a group of salt-tolerant trees and shrubs that grow in intertidal areas (where the sea meets the land) of tropical and subtropical regions. These plants have developed unique adaptations to survive in a harsh, salty environment where soil conditions are poor and water levels are constantly changing.

Question 21

What is physiologically dry soil?

Answer

Physiologically dry soil is a type of soil that contains some water, but the water is not available for the plants to absorb because it is bound tightly to soil particles or is too salty for plants to take up. This makes it difficult for plants to grow in physiologically dry soil, as the lack of available water can lead to drought stress.

Question 22

What are the differences between primary and secondary adaptations?

Answer

Primary Adaptations	Secondary Adaptations
These adaptations occur in the initial stage when an organism enters a new environment.	These adaptations occur after the initial phase of adaptation to a new environment.
They are a result of natural selection and genetic variation.	They are a result of the interaction of organisms with the environment.
Examples include gills in fish and hydrostatic skeletons in worms.	Examples include camouflage and mimicry in animals and the development of thorns and spines in plants.

Question 23

What are the purposes of adaptation?

Answer

The purposes of adaptation are:

1. To enable organisms to survive in their environment by adjusting to the changes in biotic and abiotic factors.
2. To increase the chances of survival and reproduction, which ultimately leads to the perpetuation of the species over time.

Question 24

What is volant animal and volant adaptation ?

Answer

Volant animals are those animals that have the ability to fly or glide in the air, such as birds, bats, and insects. Volant adaptation refers to the various adaptations that allow these animals to fly or glide, such as the development of wings, lightweight skeletons, and specialized respiratory systems.

Question 25

What are air sacs?

Answer

Question 26

What are xerophytes ? Write two adaptive features.

Answer

Xerophytes are plants that have adapted to grow in dry or arid environments with scarce water resources.

Two adaptive features of xerophytes are:

1. Reduced leaves: Xerophytes have small leaves or no leaves at all to reduce the surface area of transpiration and conserve water.
2. Succulent stem: Xerophytes have a thick, fleshy stem that stores water to survive during dry periods.

Question 27

What are hydrophytes? Give two examples of hydrophytes.

Answer

Hydrophytes are plants that are adapted to grow in water or in soil that is permanently saturated with water.

Two examples of hydrophytes are water lilies and lotus.

Question 28

Answer

The Cactus is a xerophytic plant. Three xerophytic plants are Opuntia, Agave and Yucca.

Question 29

What are the physiological adaptive modifications of cactus ?

Answer

The physiological adaptive modifications of cactus include the following:

1. Thick epidermis and waxy cuticle: The epidermis of cactus is covered with a thick cuticle and wax layer that prevents water loss by reducing the transpiration rate.
2. Reduced leaves: Cactus has reduced the size and number of leaves to minimize water loss through transpiration.

Question 30

Why the leaves of cactus are modified into spine? Write the scientific name of a Cactus plant.

Answer

The leaves of cactus are modified into spines to reduce the surface area of leaves to prevent excess water loss through transpiration.

The scientific name of a cactus plant is Cleistocactus sextonianus.

Question 31

What is phylloclade?

Answer

A phylloclade is a specialized stem structure found in certain plants, particularly in some cacti and other succulents. It functions similarly to a leaf in terms of photosynthesis and water storage, but it is actually a modified stem. Phylloclades are often flattened, leaf-like structures that are adapted to reduce water loss in arid environments while still carrying out photosynthesis. They can take on various shapes and sizes depending on the plant species and its environment.

Question 32

What are halophytes? Give two examples.

Answer

Halophytes are the plants that can survive in saline soil or water.

Examples of halophytes are mangroves and saltbush.

Question 33

What do you mean by physiologically dry soil ?

Answer

Physiologically dry soil is a type of soil where the amount of water present is not sufficient for the growth and survival of most plants due to high salt content, even though the soil may appear moist.

Question 34

What are pneumatophores ? Where is it found?

Answer

Pneumatophores are specialized root structures found in some plants, such as mangroves, that grow in swampy or waterlogged soils.

These structures grow above the water level and function in gas exchange, allowing oxygen to enter the root system and carbon dioxide to exit.

Question 35

Name a plant, which is adapted to grow in physiologically dry soil and mention two adaptive features.

Answer

One such plant is the cactus.

Two adaptive features of cactus are the presence of spines instead of leaves to reduce water loss through transpiration and the ability to store water in its thick stem.

Long Answer (LA) type questions

Question 1

(a) What is adaptation? (b) What are the relations between adaptation and evolution?

Answer

(a) Adaptation is a process of modification in living organisms that helps them to adjust to their environment and increase their chances of survival and reproduction.

(b) Adaptation is a process that allows organisms to become better suited to their environment over time. Evolution is the process of gradual change in the inherited traits of populations of organisms over successive generations. Adaptation and evolution are closely related because adaptation is one of the mechanisms by which evolution occurs. Natural selection, a key mechanism of evolution, acts on variations in traits that confer advantages or disadvantages to individuals in a particular environment, and adaptation can be seen as a result of this process.

Question 2

Answer

(a) Primary adaptation refers to the adaptation that occurs due to living in a new habitat or environment, while secondary adaptation refers to the adaptation that occurs due to the changes in the already existing habitat or environment.

(b) The aim of adaptation is to enable the organisms to survive and reproduce in their respective habitats or environments by adapting to the prevailing conditions. The ultimate goal of adaptation is the evolution of new species.

Question 3

(a) What is a volant animal? How many types of volant animals are there and what are these? (b) Describe any three adaptive features of pigeons related to flight. 

Answer

(a) Volant animals are those animals that are capable of sustained flight. There are two types of volant animals: powered flies, such as birds and bats, and gliders, such as flying squirrels and some lizards.

(b) Three adaptive features of pigeons related to flight are:

1. Wing shape: Pigeon’s wings are broad and strong, allowing them to generate lift and stay in the air for extended periods of time.
2. Light but strong skeleton: Pigeons have a lightweight but sturdy skeletal structure that allows them to maintain their shape during flight while also minimizing weight.
3. Air sacs: Pigeons, like all birds, have air sacs that help them efficiently exchange gases during flight, which aids in their endurance and flight performance.

Question 4

Discuss in brief the role of feathers, wings and air sacs in flight adaptation of pigeon. Or, Mention the role of wings and air sacs in the flight of birds. Or, Mention the role of body feathers, wings and tail feathers as external morphological features in the flight adaptation of pigeon.

Answer

The role of body feathers, wings and tail feathers

• Body feathers: These provide insulation and also help in maintaining body temperature during flight.
• Wings: The wings provide lift and thrust required for flight. The shape of wings is also important in determining the type of flight, whether it’s gliding or flapping flight.
• Tail feathers: The tail feathers help in steering and balancing the bird during flight. These feathers also play a crucial role in changing the direction of flight or manoeuvring.

Question 5

(a) What is adaptation? (b) What are the adaptations observed in cactus (xerophyte) ?

Question 6

Why xerophytic adaptations are found in hydrophytes?

Answer

Xerophytic adaptations are found in hydrophytes when they grow in regions with excess water or soil with poor drainage. This is because excess water can create hypoxic or anaerobic conditions that can cause damage to the root system. In such conditions, xerophytic adaptations such as reduced leaves, thick cuticles, and modified stems can help the plant conserve water and nutrients and survive in the wetland environment.

Question 7

(a) What is Sundari plant? (b) Mention why the adaptations of sundari plant are a mixture of xerophytes and terrestrial plants. (c) Discuss the adaptive characters of sundari plant. 

Answer

(a) Sundari plant (Heritiera fomes) is a species of mangrove tree that grows in the intertidal zones of the tropical and subtropical regions.

(b) Sundari plant grows in the intertidal zones where the soil is a mixture of freshwater and saline water. Hence, it requires adaptations to overcome both waterlogging and salt toxicity, leading to a mixture of xerophytic and terrestrial plant adaptations.

(c) The adaptive characters of Sundari plant are:

1. Prop roots: Sundari plant develops prop roots to provide anchorage in the saline soil and to trap sediments to stabilize the soil.
2. Pneumatophores: Sundari plants produce pneumatophores that grow vertically from the roots to the soil surface. These structures aid in the exchange of gases between the plant and the atmosphere.
3. Thick cuticle and sunken stomata: Sundari plant has a thick cuticle layer and sunken stomata to reduce transpiration and water loss.