Living Creatures: Exploring their Characteristics — Class 6 Science
Curiosity · Chapter 10
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5- Mathematics
- Science
- + 3 more
- 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
- Characteristics of living beings
- The shared features of all living things: movement, growth, need for food, respiration, excretion, response to stimuli, reproduction, and death.
- Stimulus
- Anything or any event that prompts a living being to respond, such as touching a hot object or a thorn.
- Germination
- The process by which a seed develops into a sprout or seedling, requiring the right amount of water and air.
- Excretion
- The removal of waste products from the body, such as sweat and urine in animals, and excess water and minerals in plants.
- Life cycle
- The series of stages a living being passes through, from its origin to producing the next generation and finally death.
- Reproduction
- The process of producing new ones of one's own kind, necessary for the continuity of life.
Extra questions & answers
What are the common characteristics of all living beings?
All living beings move, grow, need food, respire, excrete, respond to stimuli, reproduce, and eventually die; the absence of any of these marks something as non-living.
How do plants show movement even though they do not move from place to place?
Plants show movement by opening their flowers, trapping insects as in Drosera, twining around supports, and folding their leaves, as in the touch-me-not plant.
What is a stimulus? Give an example.
A stimulus is anything or any event that prompts a living being to respond, such as a thorn or a hot object; the touch-me-not plant folding its leaves on touch is a response to a stimulus.
What conditions are essential for the germination of a seed?
A seed needs the right amount of water and air for germination; in general, light is not essential for germination, though it is needed for the growth of the seedling afterwards.
Why does a seed need water to germinate?
Water softens the seed coat and helps the tiny embryo inside it to develop into a plant.
In which directions do the root and shoot of a plant grow?
The shoot grows upward and bends towards sunlight, while the root grows downward regardless of how the plant is placed.
What are the stages in the life cycle of a plant?
A plant's life cycle goes from seed to germination, growth and appearance of leaves, flowering, fruiting with seeds, and finally the death of the plant.
What are the four stages in the life cycle of a mosquito?
The four stages are egg, larva, pupa, and adult; the adult female lays eggs on or near water and the cycle continues.
What are the stages in the life cycle of a frog?
The frog passes through the egg (spawn) stage, the tadpole stage, the froglet stage, and the adult frog stage, with changes in body shape and habitat.
Why is reproduction important for living beings?
Reproduction is necessary for the continuity of life, as it produces new ones of the same kind to maintain the species.
Let us enhance our learning
1. List the similarities and differences in life cycles of plants and animals.
Similarities: Both plants and animals (i) begin life from a single starting structure - a seed in many plants and an egg or newborn in animals, (ii) pass through a series of stages of growth and development, (iii) grow in size, need food and water, respire and respond, (iv) reproduce to form new individuals of their own kind and thus continue their kind, and (v) finally grow old and die. The whole journey from the start to producing next generation and death is called a life cycle for both. Differences: (a) Plants generally start from a seed which germinates into a seedling, then grows into a mature plant that produces flowers, fruits and seeds again. Animals start from an egg or as a young one and grow into an adult. (b) Growth in plants is largely by increase in size, branching and formation of new leaves, flowers and fruits at many parts of the body throughout life; in animals growth is more limited and body shape is more fixed. (c) Many animals show striking change in body form and habitat during their life cycle called metamorphosis, for example egg -> larva -> pupa -> adult in mosquito and egg -> tadpole -> froglet -> adult frog in frog, while most plants do not change body plan so drastically though they do change from seed to seedling to flowering plant. (d) Plants make their own food and remain fixed at one place, animals move and take food from outside.
2. The table on the next page shows some data. Study the data and try to find out examples appropriate for the conditions given in the second and third columns. If you think that an example for any of the conditions given below is not possible, explain why.
S. no. | Does it grow? | Does it respire? | Example | Remarks
1. No | No
2. No | Yes
3. Yes | No
4. Yes | Yes
1. Does it grow? No, Does it respire? No - Example: stone, pencil, book, chair, water, air, car. Remarks: These are non-living things. They show neither biological growth nor respiration. Any increase in size, for example piling stones together, is not true living growth and there is no breathing. 2. Does it grow? No, Does it respire? Yes - No correct example of a living being is possible. Remarks: Respiration is a basic characteristic of all living beings and all living beings also show growth at some stage of their life. A thing that truly respires must be living and therefore it must also grow, so this combination does not occur in nature. 3. Does it grow? Yes, Does it respire? No - No correct example of a living being is possible. Remarks: Growth in living beings needs energy which comes from respiration, so any living thing that grows must also respire. An apparent growth without respiration, such as a crystal of sugar getting larger or a mound of sand growing, is not biological growth and is therefore not a living example. 4. Does it grow? Yes, Does it respire? Yes - Example: human being, cow, pigeon, bean plant, neem tree, frog, mosquito. Remarks: All living beings show both growth and respiration. They increase in size, especially when young, and they respire through lungs, gills, stomata or body surface to obtain energy.
3. You have learnt that different conditions are required for seed germination. How can we use this knowledge for proper storage of grains and pulses?
Bean seeds in the experiment only germinated when they got the right amount of water and air at a suitable temperature, and too much water or no water prevented germination. Grains and pulses are seeds and we want to prevent them from germinating during storage. So we store them in dry, cool and airtight conditions. We dry the grains well in sunlight before storing to remove moisture, keep them in airtight containers or gunny bags lined with plastic, keep the storage area cool, dry and ventilated, and protect from damp air and rain. Without sufficient water and warm moist air the embryo inside cannot become active, the seed coat stays hard and the grain does not sprout, and it is also saved from fungus and insects.
4. You have learnt that a tail is present in a tadpole but it disappears as it grows into a frog. What is the advantage of having a tail in the tadpole stage?
A tadpole lives entirely in water after hatching from the egg. It has no strong legs in the early stage. The long flat tail works like an oar and helps it to swim quickly, balance, change direction and escape from predators. It also helps in breathing and feeding movements in water. When the tadpole grows legs and becomes a froglet and then an adult frog, it starts living both in water and on land, hopping and swimming with its strong hind legs, so the tail is no longer needed and is gradually absorbed.
5. Charan says that a wooden log is non-living as it cannot move. Charu counters it by saying that it is living because it is made of wood obtained from trees. Give your arguments in favour or against the two statements given by Charan and Charu.
A wooden log is non-living, so the final conclusion of Charan is correct but his reason is incomplete, and Charu is incorrect. Movement alone is not the test for being living, because plants do not move from place to place but are living, and non-living things like a car can move with fuel. The true test is the presence of all life characteristics together: growth, nutrition, respiration, excretion, response to stimuli, reproduction and death. A log does not grow, does not respire, does not take food, does not excrete, does not respond and cannot reproduce even when given water, air and food, so it is non-living or dead. Charu is wrong because the wood was part of a living tree when it was alive, but once cut off it no longer shows any life activities, just as a fallen leaf or plucked fruit was once part of a living plant but is now non-living. So being made from a once-living material does not make the log living now.
6. What are the similarities and distinguishing features in the life cycles of a mosquito and a frog?
Similarities: (i) Both start life as eggs laid in or near water. (ii) Both pass through distinct stages and show metamorphosis with large changes in body shape and structure. (iii) Both have aquatic young stages that live in water and need air to breathe at the surface. (iv) Both change habitat as they grow, from completely water-dependent young to adults that can live outside water. (v) In both the adult can reproduce and lay eggs to start the cycle again. Distinguishing features: (a) Mosquito has four stages: egg -> larva -> pupa -> adult, and the pupal stage is a resting non-feeding stage; frog has stages: spawn or egg -> embryo -> tadpole with tail -> tadpole with legs -> froglet -> adult frog, with no pupa. (b) Mosquito larva and pupa are called wrigglers and tumblers and both live in water but come to the surface to breathe, while frog tadpole swims with a tail and later develops legs. (c) Adult mosquito is a small flying insect that lives for about 10 to 15 days; adult frog is an amphibian that can live both in water and on land for months to years and can hop. (d) The duration and appearance of each stage are very different.
7. A plant is provided with all the conditions suitable for its growth (Fig. 10.9). Draw what you expect to see in the shoot and the root of the plant after one week. Write down the reasons.
Fig. 10.9 shows a pot placed horizontally on the ground with a young plant inside. Even though the pot is horizontal, after about a week the shoot will be seen bending and growing upwards away from the ground, while the root will be seen bending and growing downwards towards the ground. Reason: Shoots show negative geotropism and positive phototropism, they grow opposite to the pull of gravity and towards light for photosynthesis. Roots show positive geotropism, they grow in the direction of gravity into the soil to fix the plant and absorb water. This was seen in Activity 10.3 where an inverted seedling bent so that the root still went down and the shoot still went up.
8. Tara and Vijay set up the experiment shown in the picture (Fig. 10.10). What do you think they want to find out? How will they know if they are correct?
In Fig. 10.10 a potted seedling inside a box gets light only through a small circular hole on one side, while the rest of the box is dark. Tara and Vijay want to find out whether the shoot of a plant moves and grows towards light. They will keep the plant watered and observe for several days. If they are correct that the shoot is attracted to light, they will see the shoot bending and growing towards the hole from where sunlight enters, while the root continues to grow downwards. If the shoot stays straight and does not bend towards the hole, their idea would be wrong. Comparison with a plant kept in uniform light from all sides, where the shoot grows straight up, will confirm the effect of directional light.
9. Design an experiment to check if temperature has an effect on seed germination.
Aim: To test whether temperature affects germination. Materials: three identical pots or petri dishes with same garden soil, same number of healthy bean seeds, water. Method: (i) Sow equal numbers of seeds in each pot and give exactly the same amount of water, just moist, and keep all pots where they get the same air. (ii) Keep pot A in a very cold place such as inside a refrigerator at about