Correct Answer: Option 4 a rapid rise in the number of blood cells

Homeostasis means steady state. Options 1, 2, and 3 are all about homeostasis. All are normal occurrences in the body. The primary function of the red blood cells, or erythrocytes, is to carry oxygen from the lungs to body tissues and to transfer carbon dioxide from the tissues to the lungs. The normal RBC count of adult males is 4.6 - 6.0 million, while for adult female it is 4.2-5.0 million. Normal physiological increases in the RBC count occur at high altitudes or after strenuous physical training. At high altitudes, less atmospheric weight pushes air into the lungs, causing a decrease in the partial pressure of oxygen and hypoxia. With strenuous physical training, increased muscle mass demands more oxygen. Smokers also have a higher number of red blood cells than non-smokers. The normal increase in RBC count is due to body's initiative to maintain homeostasis.

Correct Answer: Option 3 The two cells that result will have identical DNA.

Budding is a form of asexual reproduction. The new organism is naturally genetically identical to the primary one (a clone). When yeast buds, one cell becomes two cells.

The simple cell division of a yeast cell is through the pinching of small bud cells from a parent cell. Meiosis is absent because it usually occurs in sexual reproduction. Therefore, option 4 is incorrect.

Correct Answer: Option 4 liver cells use different genes than muscle cells

Genes are turned on or off for cellular differentiation. For example, to produce the specialized liver cells, only a fraction of the genes are expressed (through transcription with the aid of enzymes) to generate the specific structure and function of the cell. To produce the muscle cell, another set of genes of the DNA are "turned-on" (while the genes coding for the liver are not expressed) to make its specific structure and function.

The other options are invalid.

Correct Answer : Option 4 mitosis and differentiation

Correct Answer: Option 4 transport of oxygen through a placenta to a fetus

The placenta's primary role is to ensure that oxygen is moved into the fetus' blood stream and carbon dioxide is carried away from the fetus. This is an adaptation of the body to make the fetus better suited to its habitat (the womb).

Option 1 is incorrect. Production of zygotes in ovaries is not a product of evolution but of fertilization.

External fertilization of gametes of ovipary is not a characteristic of human females. They exhibit vivipary, wherein the fertilization of eggs happen internally. Hence, option 2 is incorrect.

The mammary gland or breast is another structure important to human reproduction, although it is not part of the reproductive tract itself. There if no direct connection from the mammary gland to the fetus during conception. Thus, option 3 is incorrect.

Correct Answer: Option 1 A

Structure A is the uterus. Progesterone converts the endometrium (thick lining of the uterus) to its secretory stage (placenta) to prepare the uterus for implantation. It also decreases contractility of the uterine smooth muscle. On the other hand, the estrogen regulates the production of progesterone over the full term.  As estrogen is produced by the placenta, progesterone production is stimulated and regulated. Apart from this, estrogen plays a very important role in the development of the fetus.  Without estrogen, the lungs, kidneys, liver, adrenal glands and other organs would never be triggered into maturation.  In fact, the placenta itself would never grow and operate properly if not for estrogen.

There are no known direct functions of these two hormones for the rectum (C), vagina (B) and oviduct (D) during fetal development.

Correct Answer: Option 3 Vaccines cause the production of specific molecules that will react with and destroy certain microbes.

A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains a small amount of an agent that resembles a microorganism. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters. Vaccines can be prophylactic (e.g. to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).

Correct Answer: Option 1

This diagram shows sexual reproduction. Prior to fertilization the chromosome numbers of the sperm cell and the egg cell are divided into two through meiosis. Each of the parents has different genetic information which is represented by the two different lines inside the cells. During fertilization, there is fusion of two gametes and the restoration of the original number of chromosomes. In the illustration, the zygote has the combination of the chromosomes of the parents.

Correct Answer: Option 2 The process represented is photosynthesis and the primary source of energy for the process is the Sun.

Photosynthesis is a process that converts carbon dioxide and water into glucose and oxygen, using the energy from sunlight. The equation of photosynthesis is as follows:

Thus, options 3 and 4 are invalid.

Option 1 is incorrect because respiration can occur even without sunlight.

Correct Answer: Option 1 A→C→G

From the seminiferous tubules of a testis, the sperm pass into the coiled tubules of the epididymis(A), which stores the sperm and where they gain motility and ability to fertilize. During ejaculation, the sperm goes to the muscular vas deferens (C). These ducts run from the scrotum around and behind the urinary blader, where each joins a duct from the seminal vesicle, forming the ejaculatory duct. The ejaculatory duct opens into the urethra (G) then runs through the penis.