# Homeostasis | Short Questions and Answers

Homeostasis | Short Questions and Answers. This post about FSc. Part-II Biology Chapter No.15: (Homeostasis).

The following objective questions and answers are very important for 2nd Year, Biology, for the final examinations of all Boards of Punjab as well as Pakistan:

### Chapter No.15: Homeostasis

Q.1: Compare the controlling system of refrigerator with the controlling system of man?
The thermometer of the refrigerator acts as a receptor of man. The thermostat acts are the control center of man. And its cooler or heater acts as effecter of man.

Q.2: Why do some marine fishes retain trimethylamine oxide instead of urea?
Urea is harmful in high concentrations. So, these fish retain another chemical called trimethylamine oxide. This compound protects the fishes against the harms of urea.

Q.3: How cactus is able to survive in dry conditions?
Cacti shed their leaves during the dry seasons. Therefore, transpiration is stopped completely. They have stem as their photosynthetic organ. Their stem store water in the rainy season and use it in dry condition.

Q.4: Why do animals living in low supply of water secrete urea?
Ammonia cannot be kept as an excretory product in a low supply of water. So, it is changed into a less toxic substances like urea. Urea requires only 50 ml of water for the removal of 1 gm of nitrogen.

Q.5: What is deamination? Which compound is produced during deamination?
The catabolism of amino acid release amino group (-NH2) during deamination.

Q.6: How does skin act as an organ of the thermoregulation in mammals?
In the case of overproduction of heat, the blood supply is increased to the exposed surface area of skin. So, heat is dissipated and the temperature is lowered by evaporative cooling. Thus, the skin of the mammals acts as an organ of thermoregulation.

Q.7: What is a counter-current mechanism?
The opposite flow of adjacent fluid that maximizes the transfer rate is called the counter current mechanism.

Q.8: Why do biologists face difficulties in the use of the old temperature classification system of animals?
It is observed that deep-sea fishes have constant natural surroundings. Thus, their body temperature remains constant. Lizard regulates their body temperature. The temperature of numerous birds and mammals change also.

Q.9: Define homeostasis?
The protection of the internal environment from the harms of fluctuations in the external environment is termed as homeostasis.

Q.10: Define osmoregulation?
It is the regulation of water and solutes between organisms and their environment.

Q.11: What is haemodialysis?
In haemodialysis blood is circulated through a dialyzer called an artificial kidney. The dialyzer has two spaces separated by a thin membrane. Blood passes from one side of the membrane and dialysis fluid in the other. The wastes and excess water pass from the blood through the membrane into the dialysis fluid.

Q.12: What are heterotherms?
Heterotherms are those animals that are capable of varying degree of endothermic heat production but generally do not regulate their body temperature within the narrow range e.g. bats, humming bird etc.

Q.13: What are pyrogens? Or What is pyrexia?
In bacterial and viral infections, leukocytes increase in number. These pathogens and the blood cells produce chemicals called pyrogens. Pyrogens displace the set point of hypothalamus above the normal point of 37^\circ C .

Q.14: Name the excretory structures in the animal Kingdom that are associated with the digestive tract?
Malpighian tubules in insects are found to be associated with the digestive tract.

Q.15: Define excretion?

The mechanism which eliminates nitrogenous waste is referred to as excretion.

Q.16: Define thermoregulation?
The maintenance of internal temperature within a tolerable range is designated as thermoregulation.

Q.17: What is hypotonic environment?
When the external environment has more water or a diluted solution compared to the cell concentration, it is designated as a hypotonic environment.

Q.18: What is hypertonic environment?
When there is more concentrated external environment or solution than cell concentration it is termed as hypertonic environment.

Q.19: What is isotonic environment?
When external solution concentration resembles to the internal solution, it is known as isotonic environment.

Q.20: What are hydrophytes?
Hydrophytes have the adaptations to remove the flooding of its cells in freshwater. In this type, the surface area of leaves is very large to transpire water excessively. Extensive stomata are present on the upper surface facing the atmosphere to promote loss of water, for example, water lilies.

Q.21: What are mesophytes?
Mesophytes have moderate water availability. In cases of sufficient supply of water stomata are kept open to promote loss of excess water, however, in restricted supply stomata close to prevent the loss, for example rose, mango, brassica, etc.

Q.22: What are xerophytes?
Xerophytes have adaptations for a reduced rate of transpiration. Many possess small, thick leaves. Their cuticle is thick, waxy, and leathery. Stomata are on the lower surface of leaves and located in a depression. In the rainy season, they store water for use in dry conditions e.g. cactus.

Q.23: In what form nitrogen is excreted by animals?
Mostly excess nitrogen is excreted by animals as ammonia, urea, or uric acid. Lower quantities of nitrogen are excreted in the form of creatinine, creatine, or trimethylamine oxide and in very small quantities as amino acids, purine, and pyrimidine.

Q.24: What is metanephridium?
The earthworm is the ideal example of tubular excretory system called metanephridium. This system has an internal ciliated opening nephrostome which is immersed in coelomic fluid and enveloped by a network of capillaries. Nephrostome collects coelomic fluid.

Q.25: What are malpighian tubules?
Terrestrial arthropods particularly in the insects, the excretory structures are adapted to collect excretory products from hemolymph in sinuses through suspended tubular structures called malpighian tubules.

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The remaining short questions and answers of Chapter No.15 (Homeostasis) will be uploaded soon Insha Allah.