Give reasons for the following:-
I) Meristematic cells have a prominent nucleus & dense cytoplasm but they lack
Vacuoles.
ii) Animals in colder regions & fishes of cold water have thick layer of
Subcutaneous fat.
Iii) Cork acts as a protective tissue.
Iv) You can fold the pinna of your ear but cannot bend the bones in your arms.
Please give the answer asap
Answers
1).Meristematic cells are continuously dividing cells so they have a prominent nucleus and dense cytoplasm. But since these cells do not store food material or waste materials, they lack vacuole. Sclerenchyma cells have lignified cell walls which makes them compact and leaves no intercellular spaces
2).Animals in colder regions and fish of cold water have thick subcutaneous fat layer because fat acts as a good insulator and trap the body heat under the skin. This helps them survive in colder temperatures.
3).It is since our ears have cartilage matrix that provides flexibility as it is made of sugar and proteins which means they can be bent whereas, the bone matrix does not allow any kind of flexibility as it is made of calcium and phosphorus compounds and hence, cannot be bent.