Answer:
Sometimes molecules cannot move through the cell membrane on their own. These molecules need special transport proteins to help them move across the membrane. Facilitated diffusion is the diffusion of substances with the help of transport proteins in the plasma membrane. These special proteins are called channel proteins or carrier proteins, and they are attached to the cell membrane. In fact, they go through the cell membrane, from the inside of the cell to the outside. Facilitated diffusion is used for molecules that cannot diffuse rapidly through cell membranes on their own, even when the molecules are moving from high to low concentration areas. An example is the sugar plants and animals use for energy, called glucose. Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient so it does not require the use of cellular energy.
Answer:
According to the hormone diagram of the menstrual cycle, the woman is not pregnant due to the behavior of progesterone and estrogens, whose levels do not increase, in addition to the absence of human chorionic gonadotropin.
Explanation:
The graph shows the behavior of hormones during a woman's menstrual cycle in the absence of pregnancy.
During a woman's normal cycle, estrogen, luteinizing hormone (LH) and follicle stimulating hormone (FSH) tend to increase prior to ovulation, reach their peak values at ovulation, and then decline, as shown in the graph. Progesterone, on the other hand, increases after ovulation and decreases if the woman does not become pregnant.
In the case of a pregnant woman:
- <u>Estrogens</u> continue to increase after ovulation, produced by the ovaries and placenta.
- <u>Progesterone</u> also increases its levels, as it is a hormone produced by the ovaries and placenta.
- <u>Hormone human chorionic gonadotropin</u> (HCG) appears and increases during pregnancy, due to the secretory activity of the placenta.
<em><u>The diagram represents the normal cycle of a woman who is not pregnant</u></em>.
The liver can regenerate up to half of itself
Answer:
Option 1.
Explanation:
r-selected species may be defined as the species that has higher growth rate, shows less parental care and the rate of survival of the off spring is low as compared with k selected species.
Black widow spiders have the ability to produce 1000 offspring. Their chances of survival are extremely low and only few species of black widow spiders survive. Hence, black widow spider is r-selected species.
Thus, the correct answer is option (1).
