Science [2 Mark Questions]

Two main causes of a person developing near sightedness also known as Myopia are
i. Excessive curvature of eye lens
ii. Elongation of eyeball
Can be corrected by using concave lens which is a divergent.

Hawk gets more energy in food chain having three trophic levels.


Energy available to hawk is 1J in the food chain with three trophic levels, but it is 0.1 J in the food chain with four trophic levels.
This is due to 10% energy law which states that only 10% energy is available at the next trophic level from the previous level.

A - Phytoplankton; C - Small fish D - Secondary carnivores; B - Herbivores

The nature of the lens is concave, i.e., it is a diverging lens.

In the liver, urea is formed during the ornithine cycle and is sent to the kidneys for elimination through the blood stream. It also serves to excrete cholesterol, bile pigments, vitamins and drugs. These substances are secreted in the bile and are taken to the intestine. Then they are eliminated along with faeces.

Glucose along with filtrate runs down through the long renal tubule by the action of cilia. Glucose, amino acids, salts, etc., are reabsorbed by the tubular cells and then secreted into the capillary blood cells by diffusion.

In a flower fertilisation requires both male and female gametes. If pollination does not occur, male gamete is not available hence fertilisation cannot take place.