Cell membranes are made of phospholipids to keep the cell's water (cytoplasm) in and everything else out. so your answer would be D <span />
<span>The answer to 10 is A as liquids expand with an increase in temperature. 12. Not able to answer. The answer to 17 is A as a the two different metals expand and contract at different rates when heated and cooled.</span>
The answer to this question is the term rhizome. A rhizome is a stem of a plant that is growing underground and is growing horizontally. It is also known as rootstocks. The rhizome's function in the plant is that it is used to store starches and protein that enables the plant to grow underground.
Most of the time m (M) means male and f (F) means female.
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.
