Answer:
(2) low power: 100 small pollen grains
high power: 25 large pollen grains
Explanation:
Compound light microscopes are devices used to greatly magnify objects. They have several objective lenses, a low-power lens magnifies 10 times (10X) the objects, and the high-power lens magnifies them 40 times (40X).
For that reason, when observing the pollen grains with the high-power lens the student will see them bigger than with the low-power lens. However, the field of view (the visible area through a lens) is reduced when a higher power lens is used, so fewer pollen grains will be seen.
The answer therefore is the option of higher number of pollen grains of small size for the low-power lens, and lower number of pollen grains of larger size for the high-power lens.
Answer: E
<span>Neurons are cells
that facilitate communication from one part of the body to another and signals
are send as mean of communication which can be achieved through electrical
potentials. Thus, cell membrane around the neuron usually create ionic potentials
by separating various ions across tis cell membrane. However, the place where
most processes that involved in neuronal preservation and functioning are
triggered is known as neuronal membrane.</span>
During the repolarization phase of an action potential which of the following is the primary activity in the membrane of the post-synaptic cell?
A) Sodium ions are flowing out of the cell.
B) Sodium ions are flowing into the cell.
C) Potassium ions are flowing into the cell.
D) Potassium ions are flowing out of the cell.
Answer:
D) Potassium ions are flowing out of the cell.
Explanation:
The threshold opens both voltage-gated Na+ channels and the voltage-gated K+ channels. The voltage-gated K+ channels are very slow in opening. Therefore, they open when the voltage-gated Na+ channels are closing. The opened voltage-gated K+ channels are responsible for the repolarizing phase.
During this phase, the inflow of Na+ becomes less as the responsible channels are inactivated. The opened K+ channels allow the K+ to move out of the post-synaptic cell. It results in the generation of negative charge inside the cell membrane as the membrane potential reduces +30 mV to −70 mV.
Answer:
d. Two of the above explanations are correct.
Explanation:
A frameshift mutation is commonly known as a genetic mutation that occurs as a result of the indels such as the addition or removal of certain nucleotides in the sequence of a DNA that is indivisible by three. In the presence of addition or removal, the reading frame from the initial translation to a different one. Thus, the correct option is option d.
Answer:
Black
Explanation:
In the mouse a certain colorless pigment precursor exists.
- If the B allele is present: precursor is converted into black pigment.
- If the genotype is bb: albino
In addition:
- If the A allele is present: black pigment is converted to brown pigment
- If the genotype is aa: black pigment is not converted and mouse remains black
If the mouse has a genotype aaBB, the colorless pigment is converted to black (because there is at least one B allele) but the black pigment cannot be converted into brown (because there's no A allele), so the mouse will have black fur,
