Biology Study Set 13
Quiz 28 :
Plants are sedentary. Unlike animals they cannot escape from enemies by running or fighting. But different plants have their own methods of defense. Some plants produce signaling molecules to protect it. These signaling molecules are given out during threatening situations. In the given case, plants produce the signaling molecules to save it from the caterpillars. This particular trait might have acquired by the plant by a mutation. It became a favorable adaptation for those plants living in areas infested with caterpillars. Those plants could signal the wasps to lay eggs inside the caterpillars and survive better in the struggle for existence. Nature selects these fittest ones to continue its generations. The theory of natural selection states 1. There is over production of off-springs. 2. Off-springs are with variations. 3. The members struggle for existence 4. Those with favorable variations survive or fittest ones survive 5. Nature selects the fittest to survive or natural selection occurs.
Body of all living organisms is made up of cells. They are the structural and functional unit of all living organisms. Growth occurs when size of the body increases. This increase in size is possible only when number of cells become more. The increase in volume also results in increase in size. Therefore, growth is the result of increase in number, size and volume of cells in plants and animals whereas differentiation is changes in the cells to take up various functions. Formation of a young one from the one celled zygote by growth and differentiation is development. Hence, option (a) is correct.
Both Oryx lencoryx and Acacia tortilis will have ways to reduce water loss from the body. Their body may be able to retain water. They may have high tolerance to temperature. They may have some cooling mechanism in the body for homeostasis. Plant is with cuticle covering to prevent water loss. In Acacia , leaf lamina does not remain long. The petiole looks like leaf thus reducing stomata and evaporation through stomata. Transpiration is lowest. Root system is highly developed. It can penetrate deep down to reach the soil water available to plants. The animal may not have more sweat glands and may have cooling mechanism. Urine will be hypertonic. Animal will be active when sun rays are tolerable.