Explain how different organisms carry out exchange of gases. Give one example of each.
2. Animals grow only till a particular age whereas plants grow throughout their life. Justify.
3. (a) A plant grows towards sunlight. Mention the stimulus and the response. (b) What is meant by 'stimulus' and 'sensitivity'?
4. (a) Which characteristic of living things is shown in the Fig. (a) given alongside? (b) Distinguish between 'tissues' and 'organs'.
5. (a) What is the common feature in living things and non-living things? Fig. (a) (b) Give any four differences between living things and non-living things.
Answers
Q.1 ans ) In animals, gas exchange follows the same general pattern as in plants. Oxygen and carbon dioxide move by diffusion across moist membranes. In simple animals, the exchange occurs directly with the environment. Earthworms exchange oxygen and carbon dioxide directly through their skin.
Q.2 ans ) Answer: Animals grow for a limited period of time after which their growth ceases and they ultimately die. Plant growth is unique because plants retain their capacity for unlimited growth throughout their life. This ability of plants is due to the presence of meristematic tissue at certain locations in their body.
Q.3 a ans ) Phototropism is the growth of an organism in response to a light stimulus. Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism (skototropism).
b ans ) In physiology, a stimulus is a detectable change in the physical or chemical structure of an organism's internal or external environment. The ability of an organism or organ to detect external stimuli, so that an appropriate reaction can be made, is called sensitivity (excitability).
Q.4 a ans ) The fig is not given
b ans ) A group of cells working together is defined as a tissue and several tissues working together comprise an organ.
Q.5 a ans ) Both posses mass, shape and occupy space. 2. both are made up of basic structural units- cells in living and molecules in the non- living things.
b ans ) Living things :
1. Living things exhibit locomotory motion, they move. Animals are able to move as they possess specialized locomotory organs, for example – Earthworms move through the soil surface through longitudinal and circular muscles. Plants move in order to catch sunlight for photosynthesis
2. Living things respire. Respiration is a chemical reaction, which occurs inside cells to release energy from the food. Transport of gases takes place. The food that is ingested through the process of digestion is broken down to release energy that is utilized by the body to produce water and carbon dioxide as by-products.
3. Living things are sensitive to touch (and other stimuli as well) and have the capability to sense changes in their environment.
4 .They grow. Living things mature and grow through different stages of development.
Non-Living things :
1. Non-living things are lifeless. They do not have cells, and there is no protoplasm which forms the basis for life to exist.
2. Lack of protoplasm leads means no metabolic activities.
3.They do not have a definite and certain size of their own. They take the shape of the substance they are contained in, for example, a liquid takes the shape of its container. Stones, rocks and boulders are moulded by the changing environment and landscape. The change in the state of a non-living thing is due to an external influence.
4. Non-living things “grow” by accretion. It occurs through adding materials externally. For example, A snowball may increase in size due to the accumulation of smaller units of its own to its outer surface.
Non-living things are lifeless. They do not have cells, and there is no protoplasm which forms the basis for life to exist.
Lack of protoplasm leads means no metabolic activities.
They do not have a definite and certain size of their own. They take the shape of the substance they are contained in, for example, a liquid takes the shape of its container. Stones, rocks and boulders are moulded by the changing environment and landscape. The change in the state of a non-living thing is due to an external influence.
Non-living things “grow” by accretion. It occurs through adding materials externally. For example, A snowball may increase in size due to the accumulation of smaller units of its own to its outer surface.
Non-living things are lifeless. They do not have cells, and there is no protoplasm which forms the basis for life to exist.
Lack of protoplasm leads means no metabolic activities.
They do not have a definite and certain size of their own. They take the shape of the substance they are contained in, for example, a liquid takes the shape of its container. Stones, rocks and boulders are moulded by the changing environment and landscape. The change in the state of a non-living thing is due to an external influence.
Non-living things “grow” by accretion. It occurs through adding materials externally. For example, A snowball may increase in size due to the accumulation of smaller units of its own to its outer surface.
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