Question

How does citrate from the citric acid cycle affect glycolysis?; Why might negative feedback mechanisms be more common than positive feedback mechanisms in living cells?

a) Activates glycolysis; Negative feedback maintains homeostasis
b) Inhibits glycolysis; Negative feedback inhibits excess production
c) Activates glycolysis; Positive feedback enhances metabolic activity
d) Inhibits glycolysis; Positive feedback accelerates enzyme activity

Answer 1

Citrate from the citric acid cycle can inhibit glycolysis by affecting the activity of phosphofructokinase. Negative feedback mechanisms are more common than positive feedback mechanisms in living cells to maintain homeostasis.

Step-by-step explanation:

Citrate from the citric acid cycle can inhibit glycolysis by affecting the activity of the enzyme phosphofructokinase, which is a key regulator of glycolysis. High levels of ATP, citrate, or a lower, more acidic pH decrease the activity of phosphofructokinase, thus inhibiting glycolysis. In addition to citrate, other factors such as ATP and ADP levels also affect the efficiency of the citric acid cycle and its products.

Negative feedback mechanisms are more common than positive feedback mechanisms in living cells because they help maintain homeostasis. Negative feedback mechanisms work to counteract any deviation from the optimal state, ensuring stability and preventing excess production or activity. Positive feedback mechanisms, on the other hand, enhance or amplify the initial stimulus, which can lead to unstable conditions.

The correct option is B.