During the warm temperatures of summer, the arctic fox produces enzymes that cause its fur to become reddish-brown. during the cold temperatures of winter, these enzymes do not function. as a result, the fox has a white coat that blends into the snowy background. what explains this change in color?
the genes of a fox are made of unstable dna
mutations can be caused by temperature extremes
random alteration of dna can occur on certain chromosomes
the expression of certain genes is affected by temperature

the expression of certain genes is affected by temperature

Explanation:

For organisms to survive changing environmental conditions, a lot of molecular processes occur in the genes.

For the arctic fox, enzymes coded by specific genes are periodically "switched on or off" depending on the temperature.

Thus, the change in colour can be EXPLAINED by the expression of certain genes affected by temperature

the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.