Answer:
There is no regulatory protein that oxidizes these Calvin cycle enzymes; oxidation is spontaneous.
Explanation:
Four enzymes of the Calvin cycle are regulated by sunlight. These enzymes are namely Ribulose 5-phosphate kinase, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase, and glyceraldehyde 3-phosphate dehydrogenase.
The inactive form of these enzymes has disulfide bonds between two Cys residues. In the presence of sunlight, the reduced thioredoxin that obtains electrons from PS-I via ferredoxin reduces the disulfide bonds between the Cys residues of these enzymes.
The reduction of the bonds brings about the confirmation changes to make the enzyme active.
At nightfall, these bonds are spontaneously re-oxidized and there is no reduced thioredoxin available to reduce them again. The spontaneous oxidation of the disulfide bonds of these enzymes at nightfall makes them inactive again.
I believe, from a population that is uniformly distributed through its habitat a biologist can infer that it has reached it's carrying capacity. Population distribution describes how the individuals are distributed, or spread through out their habitat. Population size and population measure are important measures of the population. When the population is uniformly distributed, it means that they are evenly spaced over the area they occupy, thus the individuals compete for a scarce environmental resources, such as water in a desert.
Answer:
Option D, has only a single opening
Explanation:
A gastrovascular cavity has only one opening. The food goes in and comes out of the same opening there by making it a two way digestive tract.
However, a digestive tube is a one way digestive tract where the food goes in from mouth (one end) and comes out of anus (second end) . It is also called as alimentary canal
Hence, option D is correct
Ribosomes.
The outer face of RER ( rough endoplasmic reticulum) is studded with Ribosomes.