Answer:
b. A deep, narrow river divides a population of hummingbirds.
Explanation:
Hummingbirds can fly across the river. The deep and narrow river can not separate a population of hummingbirds into two patches since hummingbirds from one side of the river can fly and reach to the other side of the river.
Without any geographical isolation, hummingbirds can continue to interbreed among themselves. The continued interbreeding would not allow their reproductive isolation and thereby would prevent the allopatric speciation.
Negative impact on the environment by dams:
We all know that dams are important where there is heavy flow of water. Dams also have negative impact which are numerous and varied. They create impact on biological, chemical and physical properties. When dams are built across the river, fish migrations are affected. They also trap the sediments which affects the physical processes.
The temperature changes, composition of chemicals and the dissolved oxygen levels are not suitable for aquatic plants and animals. Due to the downstream of riverbed in dams it may affect more than 100 kilometers below a dam.
Thus, we can conclude that construction of dams can affect aquatic species, loss of forest, wetland and farmland and extinction of birds in the floodplains.
Answer:
e. sympatric, temporal
Explanation:
Sympatric is when the species are not isolated physically form one another and prevented from mating with each other another. But because they mate at different seasons, it means temporal reasons prevent them from mating with each other.
Answer:
The correct answer would be a.Resting membrane potential (RMP).
Resting membrane potential (RMP) refers to the potential difference found across the cell membrane of cell at rest.
It is created due to the unequal distribution of ions (such as Na⁺, K⁺, Cl⁻, Ca⁺⁺ etc) across the plasma membrane. It depends on the concentration gradient of ions across the plasma membrane as well as on its permeability for each type of ion.
The value of RMP may vary with the type of cell for example, RMP for neuron is around -70 mV, for skeletal muscle it is around - 90 mV etc. Negative value suggests that there is an excess of negative charge inside the cell as compared to the outside of the cell.
