Patterns in Life Diversity and Classification Class 9 Question Answer Science Exploration Chapter 12

Chapter-wise NCERT Solutions for Class 9 Science Exploration Chapter 12 Patterns in Life Diversity and Classification Question Answer NCERT Solutions are useful for focused study.

Class 9 Science Exploration Chapter 12 Question Answer

Class 9 Science Ch 12 Patterns in Life Diversity and Classification Question Answer

Patterns in Life Diversity and Classification Class 9 Questions and Answers (Exercise)

Revise, Reflect, Refine (NCERT Textbook Page No. 249)

Question 1.
Meena and Han observed an animal in their garden. Han called it an insect while Meena said it was an earthworm. Choose the correct option which confirms that it is an insect.
(i) Bilateral symmetrical body
(ii) Body with jointed legs
(iii) Cylindrical body
(iv) Body with little segmentation
Answer:
(ii) Body with jointed legs

Question 2.
Sponges represent one of the simplest animal body plans. Their bodies lack true tissues and organs. Which feature of sponge cells supports its classification under the animal kingdom?
(i) Absence of mitochondria
(ii) Ability to photosynthesise
(iii) Presence of a cell membrane
(iv) Presence of a cell wall
Answer:
(iii) Presence of a cell membrane.

Question 3.
Observe two different animals in your immediate environment. What features help you distinguish between them? How do these features help place them into different groups?
Answer:
Two animals, such as a dog and a butterfly, can be distinguished based on several features. The dog has a backbone, fur, and moves by walking, whereas the butterfly has wings, an exoskeleton, and flies.

These features help in classification as the dog is a vertebrate (having a backbone), while the butterfly is an invertebrate belonging to the group Arthropoda. Thus, differences in body structure and movement help place them into different groups.

Question 4.
How would a scientist justify choosing cellular organisation as a more fundamental characteristic for the basis of classification rather than the presence of xylem and phloem?
Answer:
A scientist would choose cellular organisation as a more fundamental basis for classification because it is a basic and universal feature of all living organisms. Cellular organisation distinguishes organisms as unicellular or multicellular, which reflects the most basic level of life structure. It applies to all kingdoms of life, including those without xylem and phloem. In contrast, xylem and phloem are specialised tissues found only in higher plants, so they cannot be used to classify all organisms.

Question 5.
You find an unlabelled slide of a single-celled organism that has a well-defined nucleus and multiple cilia. Which group would it most likely belong to? Give reasons.
Answer:
The organism most likely belongs to the kingdom Protista. This is because it is unicellular and has a well-defined nucleus, indicating that it is a eukaryote. The presence of cilia suggests that it is similar to organisms such as Paramecium, which are classified under Protista.

Question 6.
How does the diversity of organisms contribute to the balance and stability of an ecosystem?
Answer:
Diversity of organisms ensures that different ecological roles, such as producers, consumers, and decomposers, are fulfilled. Plants produce food and oxygen, animals help in pollination and seed dispersal, and microorganisms decompose dead matter and recycle nutrients. This interdependence maintains ecological balance and increases the stability of ecosystems.

Question 7.
If all unicellular organisms were grouped into a single kingdom, what problems would arise?
Answer:
If all unicellular organisms were placed in a single kingdom, several problems would arise:

• It would mix very different organisms like bacteria (prokaryotes) and protists (eukaryotes).
• Important differences in cell structure, nutrition, and reproduction would be ignored.
• It would not reflect their evolutionary relationships or complexity.
• Classification would become less accurate and confusing.

Question 8.
Viruses were studied in earlier classes. Why are they not placed in any of the five kingdoms? Give reasons.
Answer:
Viruses are not placed in any of the five kingdoms because they do not possess cellular organisation. They cannot carry out metabolic activities independently and can reproduce only inside a host cell. They show both living and non-living characteristics, which makes their classification difficult.

Question 9.
If you were asked to revise the five-kingdom classification, would you create a separate category for viruses or keep them outside the system? Justify your answer and explain what this indicates about the evolving nature of scientific classification.
Answer:
It would be appropriate to keep viruses outside the five-kingdom classification. This is because viruses lack cellular organisation and cannot survive independently. However, a separate category may be created for study purposes. This indicates that classification systems are not fixed and may change with new scientific discoveries.

Question 11.
Both pteridophytes and bryophytes lack flowers and seeds, yet they are placed in different groups. Explain this classification using their key features.
Answer:
Both bryophytes and pteridophytes do not have flowers and seeds, but they are classified into different groups based on their key features.

Bryophytes:

• Do not have vascular tissues (xylem and phloem)
• Lack true roots, stems, and leaves
• Small and simple plant body
• Require water for fertilisation.
• Example: mosses

Pteridophytes:

• Have well-developed vascular tissues
• Possess true roots, stems, and leaves
• More complex plant body than bryophytes
• Also reproduce by spores, but are better adapted to land.

Question 12.
In the classification hierarchy, which group-class or genus has fewer members but more features in common? Explain your answer.
Answer:
In the classification hierarchy, genus has fewer members but more features in common. This is because genus is a lower category than class. Organisms in the same genus are closely related and share many similar characteristics, whereas a class includes a larger number of organisms with fewer similarities. Hence, genus is more specific.

Question 13.
A scientist discovers a new organism with the characteristic features of locomotion and autotrophic nutrition. Which character(s) would help the scientist identify the organism belonging to Protista according to the five-kingdom classification?
Answer:
To identify whether the organism belongs to Protista, the scientist should look for features that match protists:

Key identifying characters:

• It is unicellular (single-celled).
• It is eukaryotic (has a well-defined nucleus).
• It may show locomotion using structures like cilia, flagella, or pseudopodia.
• It can be autotrophic or heterotrophic (some protists can photosynthesise).

Question 14.
A researcher identified a unicellular eukaryotic organism as fungi. What identification key would you suggest according to the five-kingdom classification to keep a unicellular organism in the Kingdom Fungi?
Answer:
To place a unicellular organism in Kingdom Fungi, the researcher should use identification keys based on fungal characteristics, not just being unicellular and eukaryotic.

Key identification features for Kingdom Fungi:

• Cell wall made of chitin
• Heterotrophic nutrition by absorption (no photosynthesis)
• Lack of chlorophyll
• Reproduction by spores
• Mostly non-motile

Question 15.
During a long-term ecological study, students examined organisms collected from three different environments – a freshwater pond, damp soil near decaying logs, and the digestive tract of animals. Instead of naming organisms directly, scientists recorded only structural, cellular, and nutritional features as given in the table below.

Organisms	Key Observations
P	Microscopic; no true nucleus; rigid cell covering; survives high salinity and temperature
Q	Multicellular; iflamentous body; cell wall present; no chlorophyll; grows on dead organic matter
R	Unicellular; true nucleus; contractile vacuole present; moves using flagella; shows photosynthesis in light but heterotrophic in the absence of light
S	Multicellular; well-differentiated tissues; backbone present; aquatic respiration during early life stage
T	A cellular contains genetic material; remains inactive outside a host cell

The students realised that some organisms fit neatly into Whittaker’s five-kingdom classification, while others challenged the very basis of this classification.

Based on the case study, answer the following questions –
(i) Identify one organism that clearly belongs to the Kingdom Fungi. State one observation that supports your answer.
(ii) Which organism would be placed in the Kingdom Monera? Mention one characteristic that justifies this placement.
(iii) Organisms R and Q are both eukaryotic, yet they are placed in different kingdoms. Analyse the criteria that separate them.
(iv) Explain why organism S cannot be classified using the mode of nutrition alone.
(v) Organism T does not fit into any of the five kingdoms. Which fundamental characteristic used in classification does it lack, and what does this reveal about the limitations of classification systems?
(vi) If classification were based only on habitat, which organisms might be incorrectly grouped together? Explain the scientific consequences of such a classification.
(vii) Imagine scientists discover a new organism that is multicellular, eukaryotic, lacks chlorophyll, and absorbs nutrients from a host externally. Should it be placed under fungi or animalia? Justify your reasoning using classification criteria.
Answer:
(i) The organism that belongs to the Kingdom Fungi is Q. This is because it is multicellular, filamentous, lacks chlorophyll, and grows on dead organic matter, which indicates saprophytic mode of nutrition, a characteristic feature of fungi.
(ii) The organism placed in the Kingdom Monera is P. This is because it is microscopic and lacks a true nucleus, indicating that it is prokaryotic, which is the defining characteristic of Monera. Its ability to survive in extreme conditions further supports this.
(iii) Although organisms R and Q are both eukaryotic, they are placed in different kingdoms due to differences in their level of organisation and mode of nutrition. Organism R is unicellular, has a true nucleus, and shows both autotrophic and heterotrophic modes of nutrition, which places it in Protista. Organism Q is multicellular and heterotrophic (saprophytic), which places it in Fungi. Thus, differences in cell organisation and nutrition separate them.

(iv) Organism S cannot be classified using only the mode of nutrition because mode of nutrition alone is not sufficient to classify organisms. Organism S is multicellular, has well- differentiated tissues and a backbone, which clearly places it in Kingdom Animalia. These structural features are more important than nutrition in classification.

(v) Organism T does not fit into any of the five kingdoms because it lacks cellular organisation. It is acellular and becomes active only inside a host cell, which are typical features of a virus. This shows that classification systems have limitations, as they are based on cellular organisation and cannot include entities like viruses.

(vi) Organisms from different kingdoms, such as P, R, and S, could be wrongly grouped together if only habitat is considered. For example, freshwater organisms like R and aquatic stages of S may appear similar.

Scientific consequence:
Such classification would be incorrect because it ignores fundamental differences in cell structure, nutrition, and evolution, leading to misleading relationships among organisms.

(vii) It should be placed under Kingdom Fungi.
Reason:

• It lacks chlorophyll → cannot photosynthesise
• It absorbs nutrients externally → saprophytic/parasitic nutrition typical of fungi
• Animals ingest food internally, while fungi absorb nutrients externally
• Hence, classification criteria clearly support placement in fungi.

Class 9 Science Chapter 12 Patterns in Life Diversity and Classification Question Answer (InText)

Think it Over (NCERT Textbook Page No. 228)

Question 1.
What do you understand by biodiversity?
Answer:
Biodiversity means the variety of living organisms found on Earth. It includes different types of plants, animals, and microorganisms, as well as the different habitats in which they live.

Question 2.
How does the grouping of organisms help us understand diversity?
Answer:
Grouping of organisms helps us by organising a large variety of living beings into smaller, manageable groups. This makes it easier to study their similarities, differences, and relationships, and helps us understand the diversity in a better way.

Question 3.
On what basis are plants and animals classified?
Answer:
Plants and animals are classified on the basis of their similarities and differences, such as:

• Body structure
• Habitat
• Mode of nutrition
• Presence or absence of specific features (like feathers, fur, scales, etc.)

Question 4.
How does classification help address problems in farming?
Answer:
Classification helps in farming by:

• Identifying crops and pests correctly
• Understanding the best conditions for growth
• Selecting suitable crop varieties
• Managing diseases and pests effectively

This leads to better crop production and improved farming practices.

Pause and Ponder (NCERT Textbook Page No. 231)

Question 1.
If many organisms share common features, could they also share a common ancestry?
Answer:
Yes, if many organisms share common features, they may also share a common ancestry. Similar features among organisms indicate that they might have evolved from a common ancestor over a long period of time. Although organisms adapt and change according to their environment, they often retain certain basic structural and functional characteristics.

Thus, similarities among organisms suggest evolutionary relationships and support the idea that diverse forms of life have originated from common ancestors.

Pause and Ponder (NCERT Textbook Page No. 236)

Question 2.
How can a single-celled organism carry out all its life processes when billions of cells are required to perform similar functions in multicellular organisms like us?
Answer:
A single-celled organism can carry out all life processes because one cell performs all functions needed for survival.

In unicellular organisms:

• The single cell is simple but fully functional.
• It carries out all activities like respiration, digestion, excretion, and reproduction within the same cell.
• Special structures inside the cell (organelles) perform specific functions.

For example:

• Cell membrane controls entry and exit of substances
• Cytoplasm carries out chemical reactions
• Nucleus controls activities

In multicellular organisms (like humans):

• The body has billions of cells, and each cell is specialised for a particular function.
• Different cells form tissues, organs, and systems that share the work.

Pause and Ponder (NCERT Textbook Page No. 238)

Question 3.
Which plant features reduce their dependence on water but still require moist conditions?
Answer:
Plants like bryophytes and pteridophytes reduced their dependence on water but still need moist conditions. They can live on land, but water is still required for fertilisation, so they survive in damp or moist places.

Question 4.
Why do taller plants need specialised transport tissues?
Answer:
Taller plants need specialised transport tissues because their body is large and different parts are far apart.

Xylem and phloem (vascular tissues) are required to transport water, minerals, and food efficiently throughout the plant. Xylem carries water and minerals from the roots to other parts, while phloem transports food prepared in leaves to different parts of the plant.

Question 5.
How do seeds and fruits affect where and how plants can survive?
Answer:
Seeds and fruits help plants spread to new places. Fruits protect seeds and help in their dispersal by wind, water, or animals. This allows plants to grow in different habitats, increasing their chances of survival and reducing competition with the parent plant.

Pause and Ponder (NCERT Textbook Page No. 242)

Question 6.
An earthworm (Annelida) and a beetle (Arthropoda) both have segmented bodies, but the beetle has a hard external skeleton. How does the beetle’s external skeleton help it survive?
Answer:
The beetle’s hard external skeleton (exoskeleton) helps it survive by:

• Protecting the body from injury and predators
• Preventing water loss, helping it live on land
• Providing support and shape to the body
• Allowing muscle attachment for movement.

Pause and Ponder (NCERT Textbook Page No. 247)

Question 7.
Does the term ‘biodiversity’ relate only to the variety of organisms, or does it encompass other elements?
Answer:
Biodiversity does not refer only to the variety of organisms. It also includes:

• Genetic diversity: variation within a species (differences among individuals)
• Species diversity: variety of different species in an area
• Ecosystem diversity: variety of habitats and ecosystems like forests, deserts, ponds, etc.

Question 8.
If you find a new organism in a pond, what features will you observe to classify it and
why?
Answer:
To classify a new organism found in a pond, the following features should be observed:

• Cell type: whether it is unicellular or multicellular
• Nucleus: present or absent (prokaryote or eukaryote)
• Mode of nutrition: autotrophic or heterotrophic
• Body structure: shape, presence of tissues or organs
• Movement: whether it moves and how (cilia, flagella, etc.)
• Reproduction: asexual and/or sexual
• Habitat features: how it survives in water. These features help in identifying its group and classification, because organisms are classified based on their similarities and differences in structure and life processes.

Question 9.
Why do genetic studies provide deep information about living beings?
Answer:
Genetic studies provide deep information about living beings because genes carry the hereditary information that controls all traits and life processes.

• They help explain similarities and differences between organisms.
• They show evolutionary relationships and common ancestry.
• They help in understanding how organisms grow, function, and reproduce.

Question 10.
How can changes in climate affect the biodiversity?
Answer:
Changes in climate can affect biodiversity by altering the temperature, rainfall, and habitat conditions that organisms need to survive.

• Some species may not adapt and become extinct.
• Habitats like forests, wetlands, and coral reefs may get damaged or disappear.
• The distribution of species changes as they move to more suitable areas.
• Food chains and ecosystems get disturbed.

Class 9 Science Chapter 12 Question Answer (Activities)

Activity 12.1:
Let Us Compare And Classify (NCERT Textbook Page No. 230-231) (Refer Fig. 12.2 of NCERT Textbook.)

Question 1.
Ponder on the questions given below:
Which animals can you identify in the given picture?
Answer:
The animals identified in the picture are:
Tiger, leopard, owl, eagle, dragonfly, frog, deer, snake, rabbit, firefly, birds, bear, crocodile, langur, peacock, raccoon, loris, hedgehog, bat, lion-tailed macaque.

Question.
Where are they seen?
Answer:
These organisms are seen in different habitats such as:

• Air: Eagle, owl, bat, dragonfly, firefly, and other birds are seen flying in the air.
• Land (terrestrial habitat): Tiger, leopard, deer, rabbit, bear, langur, raccoon, lion-tailed macaque, hedgehog, and peacock live on land, mainly in forests and grasslands.
• Water (aquatic habitat): Crocodile and frog spend most of their time in or near water bodies like rivers, lakes, and ponds.
• Both land and water (amphibious/semi- aquatic): Frog and crocodile can live both on land and in water.
• Trees (arboreal habitat): Langur, loris, and lion-tailed macaque are mostly found on trees.
• Ground/under bushes: Snake and some small animals like hedgehogs live on the ground or under bushes.

Question.
Which animals in the picture seem active:
(i) during the day?
(ii) during the night?
(iii) both durîng the day and night?
Answer:
(i) Animals active during the day (diurnal): Tiger, deer, peacock, eagle, langur, lion-tailed macaque, and many birds are generally active during the daytime.
(ii) Animals active during the night (nocturnal): Owl, bat, raccoon, loris, hedgehog, and firefly are mostly active at night.
(iii) Animals active during both day and night: Leopard, snake, frog, crocodile, bear, and rabbit can be active during both day and night, depending on their needs and surroundings.

Question 2.
Record your observations in Table 12.1

Answer:

Question 3.
Now, try grouping the same organisms in more than one way. Each time, change the criterion you are using for grouping (Table 12.2).
Table 12.2: Grouping the organisms

The grouping criterion	Which organisms fit in this group?	What feature or Pattern helped you decide?
Carnivore	Eagle, tiger, leopard	Eating habits
Herbivore	Deer, rabbit, langur, lion- tailed macaque	Eating habits (eat plants)
Omnivore	Bear, raccoon	Eating habits (eat both plants and animals)
Flying animals	Eagle, owl, bat, dragonfly, firefly, birds	Ability to fly
Terrestrial animals	Tiger, leopard, deer, rabbit, bear, snake, hedgehog	Live on land
Aquatic animals	Crocodile, frog	Live in water
Arboreal animals	Langur, loris, lion-tailed macaque, owl	Live on trees
Nocturnal animals	Owl, bat, raccoon, loris, hedgehog, firefly	Active at night
Diurnal animals	Eagle, deer, peacock, langur, birds	Active during the day
Animals with fur/hair	Bear, rabbit, raccoon, tiger, leopard	Body covering
Animals with feathers	Eagle, owl, peacock, birds	Body covering
Animals with scales	Snake, crocodile	Body covering.

Conclusion: Organisms in an ecosystem can be grouped in different ways based on habitat, feeding habits, and time of activity. The same organism can belong to different groups depending on the criterion used. This shows that classification is a systematic method of organising living organisms based on similarities and differences, which helps us understand biodiversity better.

Activity 12.2:
Let Us Read A Case Study (NCERT Textbook Page No. 232)

Question 1.
How are species distributed within a forest? Which plants and animals are closely linked?
Answer:
Species are not spread evenly in a forest. They live in areas where they get suitable food, shelter, and conditions. For example, hornbills are found in places with large trees and fruit-bearing plants.

Some plants and animals are closely linked (interdependent):

• Hornbills depend on fruit trees for food.
• Trees depend on hornbills for seed dispersal (spreading seeds to grow new plants).

Question 2.
How does classifying the four hombill species help us understand biodiversity?
Answer:
Classifying the four hornbill species helps scientists understand biodiversity by allowing them to study patterns such as species distribution within the forest. It also helps in identifying relationships among organisms and understanding how different hornbill species are linked to specific ecological conditions like tree size and fruit availability.

Think and discuss the case based on the following questions:
(i) How can scientists keep track of so many species?
Answer:
Scientists keep track of so many species by using biological classification and systematic methods such as field surveys, tagging, photographing, recording observations, and maintaining databases. They group organisms based on similarities and differences, which makes it easier to identify, study, and monitor
biodiversity in a structured way.

(ii) The four hornbills look similar in some ways. What features can help scientists distinguish them from one another?
Answer:
Scientists can distinguish the four hornbill species based on features such as size, colour patterns, shape and size of the beak, casque (helmet-like structure), vocal sounds, and feeding habits. Differences in their preferred habitat and nesting behaviour also help in identification.

(iii) What would happen if the large, old trees disappeared from the forest?
Answer:
If large, old trees disappeared:

• Hornbills would lose nesting sites, as they depend on tree cavities.
• Food sources would reduce, since these trees provide fruits.
• Hornbill population would decline or may even disappear from the forest.
• Other species would also be affected, disturbing the food chain.
• Overall, biodiversity would decrease, and the ecosystem would become unbalanced.

Activity 12.3:
Let Us Study (NCERT Textbook Page No. 234-235)

Question 1.
Study the concept map (Fig. 12.5).

Do it yourself (Refer to Fig. 12.5 of NCERT Textbook).
Answer:

Question 2.
List the criteria which form the basis of five kingdom classification.
Answer:
Criteria which form the basis of five kingdom classification (from the concept map).

• Cell type (prokaryotes or eukaryotes)
• Level of organisation (unicellular or multicellular)
• Cell structure (presence or absence of cell wall; type of cell wall: cellulose or chitin)
• Mode of nutrition (autotrophic producers or heterotrophic consumers/ decomposers)

Question 3.
Compare the criteria you have listed after studying the concept map and the criteria
given below:
Cell type-prokaryotic or eukaryotic
Cell structure-presence or absence of a cell wall
Level of organisation-unicellular or multicellular
Mode of nutrition-autotropic or heterotrophic
Answer:
Comparison with the given criteria.
The criteria listed from the concept map closely match the given criteria. Both include cell type, level of organisation, cell structure, and mode of nutrition. However, the concept map provides more detail in cell structure (such as cellulose in Plantae and chitin in Fungi) and also specifies the ecological role of nutrition as producers and consumers/ decomposers, along with autotrophic and heterotrophic modes.

Activity 12.4:
Let Us Explore (NCERT Textbook Page No. 235)

Aim: To observe different shapes of bacteria and cyanobacteria and compare them with the diagram (Fig. 12.6).
Observations: Different shapes of bacteria are seen, such as:

• Circular (cocci)
• Rod-shaped (bacilli)
• Spiral (spirilla)
• Comma-shaped (vibrio)
• Cyanobacteria appear as simple, microscopic
• organisms, sometimes forming chains or colonies.

The observed shapes are similar to those shown in Fig. 12.6.

Conclusion:

• Bacteria and cyanobacteria are single-celled prokaryotes.
• They are classified under the Kingdom Monera.
• They are found in almost all environments, including extreme conditions.
• Some are useful (such as in nutrient cycling and biogas production), while some are harmful as they cause diseases.

Activity 12.5:
Let Us Make (NCERT Textbook Page No. 235-236)

Aim: To prepare a hay infusion and observe microorganisms (Protists) under a microscope.

Observation:

• Tiny moving organisms are seen in the water sample.
• These organisms vary in shape and size.
• Some may move using cilia, flagella, or pseudopodia.
• On comparing with Fig. 12.7, these organisms can be identified as protists (like Amoeba, Paramecium, Euglena, etc.).

Conclusion:

• The observed organisms belong to Kingdom Protista.
• Protists are single-celled eukaryotic organisms found in water or moist places.
• They may be autotrophic or heterotrophic.
• They play an important role in aquatic food chains, oxygen production and nutrient cycling.

Activity 12.6:
Let Us Explore (NCERT Textbook Page No. 238)

Aim: To observe bryophytes and compare them with the leaves of common plants.

Observation:

• Bryophytes are small, green, and soft plants.
• They do not have true roots, stems, or leaves.
• Their leaf-like structures are simple and thin, unlike normal plant leaves.
• They lack vascular tissues (xylem and phloem).

Conclusion: Bryophytes are simple, non-vascular plants that differ from normal plant leaves in structure and complexity. They require water for reproduction, so they are called the “amphibians of the plant kingdom.” They show an early stage in the evolution of plants from water to land.

Activity 12.7:
Let Us Compare (NCERT Textbook Page No. 238)

Aim: To compare the cross-section of a fern stem (pteridophyte) with that of a sunflower stem (higher plant).

Observation: In fern stem:

• Vascular tissues (xylem and phloem) are less organised.
• They are often arranged in a simple, scattered or central pattern.
• Structure is less complex.

In sunflower stem (higher plant):

• Vascular tissues are well-developed and organised.
• They are arranged in a ring pattern.
• Presence of distinct xylem and phloem with better complexity.
  

Conclusion: The vascular tissues in ferns are simpler and less organised, whereas in higher plants like sunflower, they are well-developed and arranged in a systematic way. This shows that higher plants are more advanced in structure and function compared to pteridophytes.

Activity 12.8:
Let us Discuss (NCERT Textbook Page No. 239)

Aim: To study different leaves, observe their shape and venation, and classify them as monocots or dicots.

Observation:

• Different leaves collected from the surroundings show variation in shape and venation.
• Some leaves show parallel venation and are narrow, which are grouped as monocots.
• Some leaves show reticulate (net-like) venation and broader shapes, which are grouped as dicots.

Adaptations observed:

• Narrow leaves reduce water loss (common in grasses).
• Broad leaves help in maximum photosynthesis.
• Venation provides support and transport of water and nutrients.

Conclusion: Leaves can be classified into monocots and dicots based on their venation. Their structure helps them adapt to different environmental conditions, such as reducing water loss or increasing food production, which helps in their survival.

Activity 12.9:
Let Us Study (NCERT Textbook Page No. 239-240)

Aim: To study the salient features of faced by different plant groups-Thallophyta, Bryophyta, Pteridophyta, Gymnosperms, and Angiosperms, and analyse the adaptations and challenges faced by each group.

Answer: