1. A
2. E
3. C
4. B
5. F
6. G
7. D
Answer:
Quadrat method is used for estimating the number of individuals in an area. In this method, a large square area on the ground or water surface is marked, call it an enclave. The number of animals present in this enclave is counted. Then by assuming that the animals are less migratory and are uniformly distributed, their number for a large area is estimated by the use of unitary method of calculation. Example a 4 square feet area has 2 snails, then a 1000 square feet area will have (1000 x 2)/4, i.e, 500 snails in it. Fishes can be counted using this method only if they are confined in a small water body like a lake or a pond. Rivers are flowing so the fishes may move along its length which can give us an underestimate or an overestimate of their numbers. Sea has its depth and huge area, and fishes can be moving randomly in it. Hence this method will not work for river and sea fishes.
Explanation:
Hope this helps :D
1. Action potential reaches the axon terminal and depolarizes it.
2. Depolarization opens voltage-gated calcium channels, enabling influx of Ca into the neuron.
3. Calcium binds to specialized proteins on vesicles (containing pre-made acetylcholine) and triggers them to fuse with the neuron membrane at the synapse.
4. Exocytosis of acetylcholine into the synaptic cleft occurs.
5. Acetylcholine diffuses across the synapse and binds to nicotinic receptors on the end plate of the myocyte.
6. Activated nicotinic receptors, themselves ion channels, cause cation influx into the myocyte and generate an end plate potential. This eventually gives rise to the full depolarization within the myocyte that enables contraction.
1. Drought period - in time periods where there is more precipitation there is more water availability, and when there's not there isn't.
Floods - when there are floods there is much more water available.
Population density - in places with more population there is a greater need for water supply, while in places where there is lesser people, the water supply can be smaller.
2. The land, air, and water are heated each day by the sunlight. The heat produced by the sun that hits the earth as the earth rotates is then part kept by the atmosphere that doesn't permeate all of that heating energy.
3. By evaporation. As the sun heats the ocean, there is evaporation. As the ocean moves around with its tides there is also loss of water to the air. Also by the waves and winds there is water that's lost to the air.
4. Part of that vapour will be reabsorbed by the ocean because it cools and precipitates into the ocean. Other part of it is taken with the wind to land or to upper spheres of the atmosphere.
5. Part is reabsorbed but other part isn't. The other part is taken by the wind. As a gradient, there is less water in the air then in the ocean, keeping it above the ocean.
6. There is more water in the oceans then on the land. Water remains in the air on average about 9-10 days.
7. --------
8. An average American family uses about 300 gallons of water.
9. About 22%.
10. About 27%.
