CBSE Class 10 Answered

1) Producing more number of sperms increases the chance that some will reach a mature egg, eventually with just one being able to enter and fertilize it. During sexual intercourse, millions of sperm are deposited into the vagina. They travel through the cervix and uterus to the fallopian tubes. Fewer than 1 percent of the sperm released in an ejaculation ever make it to the egg. Factors inhibiting the success of sperm include abnormal formation and premature death from exposure to acidic vaginal secretions. Sperm can also be blocked by excess mucus covering the cervix, or they may travel to the fallopian tube that does not contain the egg. So large of sperms are produced compared to ovum so that at least a few can be successful in reaching the ovum and one can fertilise it.

2) In aerobic respiration, free or molecular oxygen is available to accept the hydrogen released in the process. This results in complete oxidation due to which large amount of energy is released. In anaerobic respiration, there is no oxygen to accept the hydrogen released in the process. This results in incomplete oxidation and carbon dioxide and ethyl alcohol are formed as by-products. Hence comparatively less amount of energy is released.

3) Potato is a tuber. A tuber is an enlarged portion of an underground stem that store food for the plant. The tuber, like any other stem, has nodes that produce buds. The eyes of a potato are actually the nodes on the stem. Each eye contains a cluster of buds. So only the pieces of potato that contain the eyes and nodes will produce new plants.