Diversity in the Living World — Class 6 Science
Curiosity · Chapter 2
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5- Mathematics
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- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
- Space weighted by chapter size
- Charts from the book's own data
- Traps corrected
Chapter summary
Key ideas & terms
- Biodiversity
- The variety of plants and animals found in a particular region.
- Venation
- The pattern of veins on a leaf; reticulate venation is net-like (hibiscus) and parallel venation has veins running parallel (banana, grass).
- Taproot and fibrous root
- A taproot has one main root with smaller side roots (mustard); fibrous roots are a bunch of similar thin roots from the stem base (grass).
- Dicots and monocots
- Plants whose seeds have two cotyledons are dicotyledons; those with one cotyledon are monocotyledons.
- Adaptation
- A special feature that enables a plant or animal to survive in a particular region or habitat.
- Habitat
- The place where a plant or animal lives, which provides food, water, air, and shelter; habitats may be terrestrial or aquatic.
Extra questions & answers
What is biodiversity?
Biodiversity is the variety of plants and animals found in a particular region.
How are plants grouped on the basis of their stems and height?
Plants are grouped as herbs (small, soft green stems), shrubs (hard woody stems branching near the ground), and trees (tall, thick, woody stems); climbers and creepers are further types.
What is the difference between reticulate and parallel venation?
Reticulate venation is a net-like pattern of veins, as in hibiscus, while in parallel venation the veins run parallel, as in banana and grass leaves.
What is the difference between a taproot and a fibrous root?
A taproot has one main root with smaller side roots arising from it, as in mustard, while fibrous roots are a bunch of similar thin roots from the base of the stem, as in grass.
What link does the chapter draw between venation, roots, and cotyledons?
Dicot plants generally have reticulate venation and a taproot system, while monocot plants have parallel venation and a fibrous root system.
What is an adaptation? Give an example.
An adaptation is a special feature that enables a plant or animal to survive in a particular region, such as a cactus storing water in its thick fleshy stem to survive the desert.
How are camels of the hot and cold deserts different?
The hot-desert camel has long legs, wide hooves, and one hump, while the cold-desert camel has shorter legs, two humps, and long hair to survive Ladakh's cold winters.
What is a habitat, and what are its two broad types?
A habitat is the place where a plant or animal lives; the two broad types are terrestrial (land) habitats and aquatic (water) habitats.
What are amphibians?
Amphibians are animals such as frogs that can live both in water and on land.
How can the loss of biodiversity be prevented?
By protecting habitats and through conservation measures such as sacred groves and government projects like Project Tiger and the Cheetah Reintroduction Project.
Let us enhance our learning
1. Here are two types of seeds. What differences do you find among the roots and leaf venation of their plants? (a) Wheat (b) Kidney beans
Wheat is a monocotyledon. Its seed has a single cotyledon. The plant develops a fibrous root system where many thin roots of similar size arise from the base of the stem, and its leaves show parallel venation where veins run parallel to each other. Kidney bean (rajma) is a dicotyledon. Its seed splits into two cotyledons. The plant develops a tap root system with one main taproot and smaller side roots, and its leaves show reticulate venation with a net-like pattern of veins on both sides of a prominent midrib.
2. Names of some animals are given below. Group them based on their habitats. Write the names of aquatic animals in the area marked ‘A’ and terrestrial animals in the area marked ‘B’. Enter the names of animals living in both habitats in part ‘C’. Horse, Dolphin, Frog, Sheep, Crocodile, Squirrel, Whale, Earthworm, Pigeon, Tortoise
Aquatic habitats are water bodies and terrestrial habitats are land. A (aquatic only): Dolphin, Whale - they live in water and cannot survive long on land. B (terrestrial only): Horse, Sheep, Squirrel, Earthworm, Pigeon - they live on land, on trees or in soil burrows, and breathe air directly. C (both aquatic and terrestrial / amphibious and semi-aquatic): Frog, Crocodile, Tortoise - they can live in water as well as on land. Frog is a true amphibian, while crocodile and tortoise spend time in water and also come onto land for basking and breeding.
3. Manu’s mother maintains a kitchen garden. One day, she was digging out radish from the soil. She told Manu that radish is a kind of root. Examine a radish and write what type of root it is. What type of venation would you observe in the leaves of radish plant?
Radish is a swollen, fleshy taproot. It is the main taproot of the plant modified to store food and appears thick and tapering with small lateral roots arising from it. Plants with taproots generally have reticulate venation in their leaves. Therefore the leaves of a radish plant show reticulate venation with a net-like pattern of veins.
4. Look at the image of a mountain goat and a goat found in the plains. Point out the similarities and differences between them. What are the reasons for these differences?
Similarities: Both are goats, mammals, herbivores, have four legs, hooves, horns, similar body plan and eat grass and leaves. Differences: The mountain goat has a thicker, longer and denser coat of hair or wool, a more compact or sturdy body, and strong, grippy hooves suited for climbing steep, rocky, snow-covered slopes in very cold conditions. The goat of the plains has shorter, thinner hair, longer legs in some breeds and is adapted to hot, dry or moderate plains. Reason: These are adaptations to their different habitats. Cold, windy, snowy mountains select for insulating fur and sure-footedness, while hot plains select for heat tolerance and grazing on flat ground. Different environmental conditions lead to different special features that help each survive in its own habitat.
5. Group the following animals into two groups based on any feature other than those discussed in the chapter— cow, cockroach, pigeon, bat, tortoise, whale, fish, grasshopper, lizard.
One possible feature is how they reproduce or body covering. For example, based on whether they give birth to young ones or lay eggs: Group 1 - Viviparous / mammals that give birth to young ones: cow, bat, whale. Group 2 - Oviparous / egg-laying animals: cockroach, pigeon, tortoise, fish, grasshopper, lizard. Another valid grouping could be: vertebrates (cow, pigeon, bat, tortoise, whale, fish, lizard) versus invertebrates (cockroach, grasshopper), or animals with wings for flying (pigeon, bat) versus animals without wings. Any consistent, logical basis other than habitat or movement is acceptable if explained.
6. As the population grows and people want more comfortable lives, forests are being cut down to meet various needs. How can this affect our surroundings? How do you think we can address this challenge?
Effects of cutting forests: Loss of habitat for plants and animals leads to loss of biodiversity, some species may disappear. Less trees means less oxygen production, more carbon dioxide, increase in temperature and climate change, less rainfall, soil erosion, floods and droughts, and loss of food, shelter and medicinal plants. It also damages the interdependence between plants and animals. Ways to address: Plant more trees and practice afforestation and reforestation, use resources sustainably and reduce wastage, recycle paper and wood products, protect habitats as sacred groves, national parks and sanctuaries, promote awareness, adopt laws against indiscriminate felling like Project Tiger and other conservation projects, and involve local communities in protection and judicious use of forests.
7. Analyse the flowchart. What can be examples of ‘A’ and ‘B’? Plant -> Does it have leaves? -> Does it have reticulate venation? -> Yes -> A, No -> B
The flowchart separates plants based on leaf venation. If a plant has leaves and the venation is reticulate, it goes to A. A therefore represents dicot plants with reticulate venation and taproots, for example hibiscus, mustard, chickpea, neem, tulsi, or kidney bean. If a plant has leaves but the venation is not reticulate, that is parallel venation, it goes to B. B therefore represents monocot plants with parallel venation and fibrous roots, for example wheat, maize, rice, grass, banana or lemongrass. If the flowchart also has a No branch for Does it have leaves, that would represent plants without true leaves such as some fungi or certain non-flowering plants, but in the context of this chapter A and B are the two leaf-venation types above.
8. Raj argues with his friend Sanjay that “Gudhal (hibiscus) plant is a shrub.” What questions can Sanjay ask for clarification?
Sanjay can ask questions that test the criteria for herbs, shrubs and trees: How tall is the hibiscus plant - is it medium height, shorter than a tree but taller than a herb? What is the nature of its stem - is it brown, hard and woody but not as thick as a tree trunk? Where do its branches arise - do many woody branches arise very close to the ground instead of a single main trunk branching higher up? Is the stem hard and can it stand erect without support? These observations help confirm that hibiscus matches the features of a shrub.
9. Based on the information in the table, find out examples of these plants for each group. Group Type of seed Type of root Examples A Dicot Taproot B Monocot Fibrous roots (a) What other similarities do plants of group A have?
Group A are dicot plants with taproots. Examples are chickpea, kidney bean, mustard, hibiscus, neem, tulsi, rose, sadabahar (periwinkle), mango and radish. Other similarities of group A plants are: they have two cotyledons in their seeds and they show reticulate venation in their leaves, where veins form a net-like pattern on either side of the midrib.
9. Based on the information in the table, find out examples of these plants for each group. Group Type of seed Type of root Examples A Dicot Taproot B Monocot Fibrous roots (b) What other similarities do plants of group B have?
Group B are monocot plants with fibrous roots. Examples are wheat, maize, rice, grass, banana, lemongrass, onion and millet. Other similarities of group B plants are: they have a single cotyledon in their seeds and they show parallel venation in their leaves, where veins run parallel to one another along the length of the leaf.
10. Observe the labelled part of a duck in the picture given below. What differences do you observe in the feet of the duck compared to the other birds? Which activity would the duck be able to perform using this part?
The duck has webbed feet where the toes are joined together by a thin membrane of skin, while the pigeon and most other land birds have separate toes with claws and no webbing. The web acts like a paddle. This adaptation helps the duck to swim efficiently, paddle and steer in water, and also to walk on mud without sinking. It is an adaptation to its aquatic habitat.