Class 10 Science Lesson 2

Exercise

1. Choose the correct options for the following questions.

a) What are the main features of organisms under kingdom Plantae?

Answer: iii. Eukaryotic cell, cell with cell wall, autotrophs

b) Why is Cycas kept in gymnosperm?

Answer: iii. Bears cones instead of flowers, seeds are naked without fruit

c) Two animals are shown here in figure. They belong to the same kingdom. What is the main reason?

Answer: ii. Multicellular and heterotrophic

d) Based on evolution, which group is most closely related?

Answer: iv. Platyhelminthes, Nemathelminthes, Annelida

e) What is the main reason for classifying whales in class Mammalia?

Answer: iv. Gives birth and suckle milk to young ones

f) Why are club mosses more advanced than mosses?

Answer: iii. Xylem and phloem tissue are found in club moss

g) To which kingdom do organisms having cell walls belong?

Answer: iv. Fungi, Plantae, Monera

h) To which class do egg-laying animals with a four-chambered heart and feathers belong?

Answer: iii. Aves

i) Which group of plants belong to angiosperm?

Answer: iv. Paddy, banana, mango

j) Which division do plants having vascular tissue belong to?

Answer: iii. Tracheophyta

2. Differentiate Between:

a. Plant Kingdom		Animal Kingdom
i) Organisms are mostly autotrophs (make their own food).		i) Organisms are heterotrophs (depend on others for food).
ii) Cells have cell walls made of cellulose.		ii) Cells lack cell walls.
iii) Usually non-motile (do not move).		iii) Mostly motile (can move).
iv) Store food mainly as starch.		iv) Store food mainly as glycogen.

 

b. Fish		Star Fish
i) Vertebrate with backbone.		i) Invertebrate without backbone.
ii) Body covered with scales.		ii) Body covered with spiny skin.
iii) Have fins and swim in water.		iii) Move slowly using tube feet.
iv) Have gills for respiration.		iv) Breathe through tube feet and skin gills.

 

c. Jelly Fish		Cuttle Fish
i) Invertebrate, belongs to phylum Cnidaria.		i) Mollusc, belongs to phylum  Mollusca.
ii) Soft, gelatinous body with tentacles.		ii) Has a hard internal shell (cuttlebone)  and tentacles.
iii) Moves by pulsating bell.		iii) Moves by jet propulsion using siphon.

 

d. Moss		Club Moss
i) Non-vascular plant (no xylem/phloem).		i) Vascular plant (has xylem and phloem).
ii) Dominant gametophyte stage.		ii) Dominant sporophyte stage.
iii) Lives in moist environments.		iii) Can grow in drier land areas.

 

e. Pinus		Peepal
i) Gymnosperm: seeds are naked (no fruit).		i) Angiosperm: seeds enclosed in fruit.
ii) Leaves are needle-like.		ii) Leaves are broad.
iii) Reproduces using cones.		iii) Reproduces using flowers.

 

f. Fish		Whale
i) Cold-blooded vertebrate.		i) Warm-blooded mammal.
ii) Breathes through gills.		ii) Breathes through lungs.
iii) Lays eggs.		iii) Gives birth to live young.
iv) Lives in water.		iv) Lives in water but breathes air.

 

g. Dove	Bat
i) Bird: has feathers and wings.	i) Mammal: has fur and wings.
ii) Lays eggs.	ii) Gives birth to live young.
iii) Warm-blooded.	iii) Warm-blooded.
iv) Flies using feathers.	iv) Flies using membranous wings.

3. Give Reasons: 

a) Living beings need to be classified.

Ans: Living beings are classified to organize the vast diversity of organisms in an orderly manner. Classification helps scientists and students to easily identify, study, and understand relationships among organisms. Without classification, it would be difficult to communicate about species or understand their similarities and differences.

b) Fucus and Marchantia look alike, but Fucus is classified as algae while Marchantia is classified as bryophyta.

Ans: Though Fucus and Marchantia look similar in their thallus structure, they belong to different groups because Fucus is an algae that grows mostly in aquatic environments and lacks specialized tissues like rhizoids. In contrast, Marchantia is a bryophyte that grows on land, has rhizoids, and shows more complex reproductive structures. Their habitat and structural differences justify their classification.

c) Gymnosperms do not bear fruit.

Ans: Gymnosperms produce seeds that are naked, meaning they are not enclosed within a fruit. Unlike angiosperms, gymnosperms do not develop ovaries into fruits. Their seeds develop exposed on the surface of cones or scales.

d) Although a crocodile has a four-chambered heart, it belongs to the reptilian class.

Ans: Crocodiles belong to reptiles because of their scaly skin, cold-blooded metabolism, and reproductive features like laying eggs on land. The presence of a four-chambered heart is an advanced feature, but it is not enough to classify crocodiles as birds or mammals.

e) Although bats and whales have dissimilar characteristics, they belong to the same class.

Ans: Bats and whales both belong to the class Mammalia because they share key mammalian features such as being warm-blooded, having hair or fur, giving birth to live young, and feeding their offspring with milk from mammary glands.

f) Riccia is an amphibian plant.

Ans: Riccia is called an amphibian plant because it can live both in water and on land during different stages of its life cycle. It grows in moist habitats and needs water for the movement of sperm during reproduction, showing characteristics of both aquatic and terrestrial plants.

g) Fern is not a flowering plant; Cycas bears flower-like cones but no fruit; banana bears flower and fruit. However, all these plants are kept in the same division.

Ans: All these plants are grouped under the division Tracheophyta because they have well-developed vascular tissues (xylem and phloem). Despite differences in reproduction, such as presence or absence of flowers and fruits, their vascular system and dominant sporophyte stage unite them under the same division.

4. Answer the Following Questions

a) Into how many divisions are the organisms in the plant kingdom divided?

Ans: The plant kingdom is mainly divided into five divisions based on their structure, reproductive methods, and presence of vascular tissue:

1. Thallophyta: Simple plants like algae without true roots, stems, or leaves.

2. Bryophyta: Non-vascular plants like mosses with simple root-like structures (rhizoids).

3. Pteridophyta: Vascular plants like ferns that reproduce by spores.

4. Gymnosperms: Seed plants with naked seeds, like pine and cycas.

5. Angiosperms: Flowering plants that produce seeds enclosed in fruits, such as mango and banana.

b) Write the main features of kingdom Plantae.

Ans: Kingdom Plantae includes multicellular, eukaryotic organisms that are mostly autotrophic and carry out photosynthesis using chlorophyll. Their cells have a rigid cell wall made of cellulose. Plants exhibit alternation of generations with both gametophyte and sporophyte stages, but the sporophyte is dominant in higher plants. They reproduce sexually through spores or seeds and can also reproduce asexually.

c) Write the similarities of plants which belong to gymnosperm and angiosperm.

Ans: Both gymnosperms and angiosperms are seed-bearing vascular plants (tracheophytes) with true roots, stems, and leaves. They have a dominant sporophyte generation and produce seeds for reproduction. Both groups have well-developed xylem and phloem for transport of water, nutrients, and food within the plant.

d) If you are given only the leaves of some plants in tracheophyta and asked to distinguish their subdivisions using taxonomic knowledge, is it possible? Give your arguments.

Ans: Yes, it is possible because leaves have distinct characteristics in different subdivisions:

• Pteridophytes have simple leaves called fronds with sporangia on their undersides.
• Gymnosperms have needle-like or scale-like leaves, which are adapted to reduce water loss.
• Angiosperms have broad leaves with distinct venation patterns (parallel in monocots and reticulate in dicots).
  So, by examining the shape, texture, and venation of leaves, one can often identify the plant’s subdivision.

e) What are the main characteristics of pteridophyta?

Ans: Pteridophyta are vascular plants that reproduce by spores instead of seeds. They have well-developed roots, stems, and leaves (called fronds). Their life cycle exhibits alternation of generations with a dominant sporophyte phase. They require moist environments for reproduction because their sperm need water to swim to the egg. Examples include ferns and horsetails.

f) Roshni observed only the flowers of a new plant and concluded that the plant belongs to monocotyledon. Is observation of only the flowers a right way to identify monocotyledon? Give reasons.

Answer:
No, observing only the flowers is not sufficient to correctly identify a monocotyledon. While flower characteristics can give some clues, monocots and dicots differ in many other features such as leaf venation, root system, and seed structure. For example, monocots typically have parallel venation in leaves, fibrous roots, and one cotyledon in the seed. Dicots usually have net-like venation, taproot system, and two cotyledons. To make an accurate identification, all these features need to be examined, not just flowers.

g) The following chart shows groups of four animals based on their habitat and type:

	Terrestrial	Aquatic
Invertebrates	Group A	Group B
Vertebrates	Group C	Group D

Question: In which group does fish belong?

Answer:
Fish belong to Group D — aquatic vertebrates because they live in water (aquatic) and have a backbone (vertebrates).

i) Digestive system is not developed in animals of phylum Porifera. How do they digest food? Write.

Answer:
Animals in phylum Porifera (sponges) do not have a digestive system. Instead, they digest food intracellularly. Water carrying tiny food particles enters through pores and flows into the central cavity. Specialized cells called choanocytes capture food particles by phagocytosis. These cells then digest the food inside themselves and distribute nutrients to other cells. This process allows sponges to obtain nutrients without a digestive tract.

j) Rakesh saw an animal while playing in the ground. How can he identify the phylum of that animal by using taxonomic knowledge of kingdom Animalia? Explain.

Answer:
Rakesh can identify the phylum by observing important features of the animal such as:

• Body symmetry: whether it is radial, bilateral, or asymmetrical
• Presence or absence of backbone: vertebrate or invertebrate
• Body segmentation: whether the body is segmented or not
• Type of body cavity: presence of coelom or not
• Type of skeleton: exoskeleton or endoskeleton
• Locomotion and appendages: presence of legs, fins, wings, or tentacles
• Reproductive method: sexual or asexual reproduction
  By comparing these features with known characteristics of animal phyla, he can identify the correct phylum of the animal.

k) Shark and whale both live in water. Based on their features, which is more developed animal? Explain with reasons.

Answer:
The whale is more developed than the shark. This is because:

• Whale is a mammal, warm-blooded, breathes air using lungs, gives birth to live young, and feeds them with milk.
• Shark is a fish, cold-blooded, breathes through gills, and lays eggs or gives birth without feeding young milk.
• Whales have a more complex circulatory system with a four-chambered heart, while sharks have a two-chambered heart.
• Whales show more advanced brain development and social behavior.
  Therefore, from anatomical and physiological perspectives, whales are more advanced animals than sharks.

l. Pictures of two animals are shown below. Compare them and answer the following questions:

i) In which phylum and class do they belong?

Animal		Phylum		Class
Bat		Chordata		Mammalia
Bird		Chordata		Aves

 

ii) Write any two similarities and dissimilarities between them.

Similarities:

1. Both have wings and can fly.
2. Both are vertebrates (have backbone).

Dissimilarities:

1. Bat is a mammal, while the bird belongs to the class Aves.
2. Bats have fur and give birth to live young, while birds have feathers and lay eggs.

iii. How does the study of these animals clarify the concept of evolution?

Ans: The study of bats and birds illustrates convergent evolution. Even though bats and birds belong to different classes, they have independently evolved wings for flight as an adaptation to similar environmental demands. This shows how unrelated species can develop similar features, providing strong evidence for evolution.

m. Explain the relation between classification of living beings and evolution.

Ans: The classification of living beings is deeply connected to evolution. Organisms are grouped based on shared characteristics, which often reflect their evolutionary relationships. Classification helps reveal common ancestry, showing how species have evolved from shared ancestors through gradual changes. It also helps us understand how traits have adapted or diverged over time due to natural selection and speciation. Thus, classification is a tool that organizes biological diversity according to evolutionary history.

n. Draw a chart to show classification of kingdom Plantae according to the five-kingdom system.

Answer:

o) Draw a chart to show classification of kingdom Animalia according to the five-kingdom system. 

Answer:

p) Look at the picture below and answer the following questions:

i) Which animal has a two-chambered heart?
→ Fish have a two-chambered heart.

ii) Which animal suckles milk to its young?
→ Tiger suckles milk to its young because it is a mammal.

iii. Write any two similarities between frogs and snakes.

1. Both are cold-blooded animals (ectothermic).
2. Both lay eggs and breathe through lungs as adults.

iv. Which of these animals have air sacs in their bodies?
→ Pigeon has air sacs in its body which help in respiration and make flight more efficient.