The answer is (A. mitosis)
Answer:
The correct answer is: B. The amount of air in a room never changes.
Explanation:
- A system is said to be in equilibrium when the net components in the system remains constant (no increase or decrease) with time.
- The air in a room never remains constant and always undergoes dynamic movement into and out of the room. At equilibrium, the net air in the room remains constant as amount of air exiting the room is balanced by the amount of air entering it.
- Evaporation of water in the form of water vapour from a cup into the atmosphere is not in a state of equilibrium as the amount of water evaporating from the cup is not replaced in the cup so there is a net decrease in water level in the cup.
- The decrease in nitrogen percentage in a room is not in equilibrium as the nitrogen concentration of the room is not constant.
- A blade of grass growing taller is not in equilibrium as a constant height of the grasses is not maintained.
The savanna grasslands of Africa is an example of a biome that supports large populations of grazing herbivores, few birds etc. The savanna supports grazing animals such as wildebeests, antelope, zebra and many other grazing species. There are few species of birds because the landscape there is almost void of trees. Only a few species of acacia dot the extensive grassland.
<u>Controlling disease in commercial fisheries</u>
Explanation:
Disease outbreaks among fishes reared lead to economic loss to the fish farmers. Optimal conditions of the pond should be maintained to prevent disease spreading.
Control of disease is very challenging because fishes are cultivated in aquaponds at high density which increases direct contact among fishes making way for spread of the disease.
Natural predators will remove infected fish quickly but manual methods are time consuming and not effective.
Various steps which can be followed for prevention of diseases like good water quality, nutrition and sanitation facilities, stocking and storing of fish, recording each detail.
At the same time, disease control can easily be done by reducing the density of the stocks, application of vaccines and antibiotics and other drugs, mechanical administration of drugs, use of probiotics etc.
