Answer:
Directional selection
Explanation:
Natural selection is of three types :
1. Stabilizing selection: in this type of selection, genetic diversity decreases as the population stabilizes on a particular trait value. Here the mean phenotype is favored.
2. Disruptive selection is a type of selection in which extreme values for a trait are favored over the mean values thus increasing the genetic variance by favoring two extreme phenotypes.
3. Directional selection is a type of selection in which a single phenotype is favored which is of the extreme phenotype over the mean phenotype.
In the given case it can be observed that the selection is favoring long necks in case of giraffes and hence, this is an example of directional selection.
Answer:Recall that the glycolytic pathway generates NADH in the cytosol in the oxidation of glyceraldehyde 3-phosphate, and NAD+ must be regenerated for glycolysis to continue. How is cytosolic NADH reoxidized under aerobic conditions? NADH cannot simply pass into mitochondria for oxidation by the respiratory chain, because the inner mitochondrial membrane is impermeable to NADH and NAD+. The solution is that electrons from NADH, rather than NADH itself, are carried across the mitochondrial membrane. One of several means of introducing electrons from NADH into the electron transport chain is the glycerol 3-phosphate shuttle (Figure 18.37). The first step in this shuttle is the transfer of a pair of electrons from NADH to dihydroxyacetone phosphate, a glycolytic intermediate, to form glycerol 3-phosphate.This reaction is catalyzed by a glycerol 3-phosphate dehydrogenase in the cytosol. Glycerol 3-phosphate is reoxidized to dihydroxyacetone phosphate on the outer surface of the inner mitochondrial membrane by a membrane-bound isozyme of glycerol 3-phosphate dehydrogenase. An electron pair from glycerol 3-phosphate is transferred to a FAD prosthetic group in this enzyme to form FADH2. This reaction also regenerates dihydroxyacetone phosphate.
Explanation:
Question: When an atom that has no charge loses two electrons, it becomes a:
A: positive ion.
B: negative ion.
C: positive isotope.
D: negative isotope.
Answer:
When an atom that has no change loses two electrons, it becomes "positive ion".
Explanation:
It is known that electrons hold a negative charge. So, when the negative charge that is electrons are taken out an atom then the number of electrons become less in number as compared to the number of protons. Hence, the atom attains a positive charge.An isotope is formed when an atom shows same number of protons and different number of neutrons. So, when an atom loses 2 electrons there will be no change in the number of neutrons. Therefore, an isotope will not form.Thus, it is concluded that when an atom with no charge loses two electrons, it becomes a positive ion.
The answer to your question is A
Answer: The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things.
Explanation: