Answer:
a) Genes b and c are farthest apart.
Explanation:
Transformation occurs when a competent bacteria cell takes up genetic material from the environment. Usually a donor cell donates its gene fragment which is then incorporated into the chromosome or plasmid of recipient bacterial cell.
Cotransformation occurs when two genes are taken up together by the recipient. The closer the genes lie to each other, more are the chances of them being taken up together. Contransformation frequency will be higher if two genes are close to each other. Here, cotransformation frequencies between three genes are given. Amongst them, the lowest frequency is 0.0064% which is present between gene b and c. Hence, gene b and c are the farthest apart.
An asteroid hitting the earth would cause a lot of dust, ash, and other debris to go into the atmosphere which would block the sun which would cause the temperature to decrease.
The question is incomplete. The complete question is:
Question: Why do organisms without oxygen need to convert pyruvate to lactate?
A) because pyruvate is toxic to the cells
B) in order to regenerate NAD+
C) in order to use lactate in the citric acid cycle
D) because lactate is needed to produce ATP
Answer:
B) in order to regenerate NAD+
Explanation:
Kreb's cycle and electron transport chain (ETC) are the aerobic stages of cellular respiration. ETC regenerates NAD+ and FAD+ by oxidation of NADH and FADH2 produced during glycolysis and Kreb's cycle. Here, oxygen serves as the terminal electron acceptor.
Glycolytic reactions use NAD+ as an electron acceptor and produce NADH. Therefore, a constant supply of NAD+ is required to sustain glycolysis. In absence of oxygen, ETC cannot occur and organisms convert pyruvate into lactate. Pyruvate is reduced in lactate and NADH serves as the electron donor. Thereby, lactate fermentation regenerates NAD+ to continue the process of glycolysis.
