ZOO502 Final Term Current Solved Paper February 2020

ZOO502 - Animal Physiology and Behavior

Q1. How alveolar collapse is prevented? (2 marks)

Prevention of Alveolar Collapse:

Alveolar collapse normally does not occur for two reasons

• Surrounding tissue prevents over-expansion of alveoli.
• Presence of pulmonary surfactants.

Q2. Peristalsis (2 marks)

The esophagus conducts the bolus by peristaltic movement. Peristaltic movements are the waves of contraction and relaxation in the smooth muscles of alimentary canal walls. These movements start from oral cavity and end at the distal end of rectum.

Q3. Three use of crops (3 marks)

In some animals, esophagus contains a sac-like expanded section, the crop, which is used to store food before digestion.

Crop is generally found in those animals that feed infrequently. It allows quantities of food to be stored for digestion at a later time

Many birds e.g. chicken. Leeches, which feed very infrequently, with weeks or months between feeding periods.

In some animals crops are also used to ferment or digest foods for purposes other than normal digestive process. For example some parent birds prepare food in this way to be regurgitated for their nestlings e.g. pigeon’s milk.

Q4. Write three type of blood vessels (3 marks)

network of blood vessels

1. arterioles,
2. capillaries
3. venules

and a network of lymph vessels, the largest of which is the central lacteal.

Blood Vessels Three types of blood vessels carry blood during circulation:

• Arteries which carry blood away from the heart to organs and tissues.
• Veins which return blood to the heart.
• Capillaries which have thin walls formed of only a single layer of endothelial cells and permit exchange of materials between blood and tissues.

Q5. Mechanism of panting (3 marks)

Temperature zone which activates evaporative heat-dissipating mechanisms.

Animals react to higher temperature by losing heat by active heat-dissipating mechanisms such as sweating or panting

temperatures above the upper critical temperature lead to hyperthermia. Hyperthermia occurs as the heat production and gain exceeds the rate of heat loss.

If evaporative heat loss mechanisms fail, hypothermia becomes lethal

Panting

• Panting involves use of respiratory system to lose heat by evaporative cooling. It occurs in mammals, birds and some reptiles.
• During panting, mammals inhale through the nose and exhale through the mouth, exposing the tongue and other mouth structures to encourage further water evaporation and therefore heat loss.
• Heat is carried away in exhalant air because the dimensions of the mouth are such that exhalant air retains the heat absorbed in the lungs.

Q6. Role of pheromones (10 marks)

Pheromones:

Chemical messengers released by many animals in environment to communicate. Spread through air.

Characteristics:

a. Affect the behavior of individuals of a species b. Effective at remarkably low concentrations c. Have particular odors d. Detected by olfactory receptors of receiving animal

Roles of Pheromones:

1. Recognize Members of Species:

Unicellular organisms recognize members of their own species. Many insects identify members of their colony.

2. Reproductive Roles:

Pheromones attract members of opposite sex for breeding. Induce courtship behaviors in members of a species. Induce spawning behavior in aquatic animals with external fertilization.

3. Territorial Behaviors:

Many male mammals mark their territories with pheromones. It warns other males of their occupied area.

4. Insect’s Social Order:

In a honeybee colony, pheromones produced by queen maintain hive's complex social order.

5. Alarm Calls:

Members of some species produce pheromones on getting injured. It warns other members by the presence of danger in area.

6. Repel Predators:

Pheromones produce by the pray may repel predators. Example: The skunks produce foul-smelling musk that makes skunks unpalatable or distasteful to their enemies.

Q7. What is kin selection give example (5 marks)

Kin Selection

Kin selection is an altruistic evolutionary strategy that favors the reproductive success of an organism's close relatives, even at a cost of organism's own survival and reproduction. Kin selection is an instance of inclusive fitness, which combines the number of offspring produced by an individual itself and the number of individuals it can ensure by supporting other close relatives (siblings). William Hamilton proposed the idea of kin (relatives) selection to explain how selection acting on related animals can affect the fitness of an individual. Through kin selection, a gene carried by a particular individual passes to the next generation through a related individual. The fitness of an individual is based on the genes it passes on as well as on those common genes that its relatives pass on. For kin selection to be effective, the individuals of a group must be able to identify their relatives. This is the reason that it is found in animals with advanced social structures i.e. primates and social insects. The altruistic kin selection behavior is most readily apparent in the act of parents sacrificing for their offspring. When parents sacrifice their own well-being to produce and aid offspring, this actually increases the fitness of the parents because it maximizes their genetic representation in the population.

Q8. four respiratory pigments (2 marks)

A respiratory pigment is a molecule, such as hemoglobin in humans and other vertebrates, that increases the oxygen-carrying capacity of the blood. The four most common invertebrate

respiratory pigments are

i. hemoglobin, ii. hemocyanin, iii. hemerythrin iv. chlorocruorin.

Q9. 4 accessory glands of alimentary canal (3 marks)

Accessory Glands: Secrete digestive juices through ducts. In mammals, the alimentary canal is associated with various accessory glands that secrete digestive juices through ducts into the gut. The accessory glands of the mammalian digestive system are: a. Three pairs of salivary glands b. Gastric glands c. Pancreas d. Liver e. Gallbladder

Q10. Aggregation with example (2 marks)

Aggregation

• An aggregation is any form of gathering of animals or the process of coming together.
• There is minimal interaction between members of an aggregation.

For example, several Drosophila flies living on a piece of rotting fruit

Q11. Difference between cortex and medulla (3 marks)

Cortex and medulla

The kidney is divided into two functional layers that contain the functional urine forming units— nephrons. The outer layer is called renal cortex while the inner layer is renal medulla.

Q12. Torpor with example (5 marks)

Torpor

Small endotherms can not maintain their high rates of metabolic rates when they are not feeding during periods of inactivity.

During those periods, some of these animals enter a state of torpor, in which body temperature and metabolic rate decrease.

The lower basal metabolism lowers the rate of conversion of energy stores into body heat.

Thus, it is generally advantageous to allow body temperature to decrease during periods of nonfeeding and inactivity.

As the animal comes out of torpor and becomes active, it undergoes a burst of metabolic activity, through shivering or oxidation of brown-fat and its body temperature rises.

Daily torpor is practiced by many terrestrial birds. The hummingbird is a classic example, allowing its body temperature to fall from a daytime level of about 40°C to a nighttime level as low as 13°C.

Several species of small mammals also undergo torpor (e.g., shrews).

Q13. Role of Appendix in digestion and function (3 marks)

The appendix is a finger-like, blind-ended tube connected to the cecum, from which it develops in the embryo. The cecum is a pouch-like structure of the colon, located at the junction of the small and the large intestines.

Appendix has no role in digestion or absorption but has an undefined role in immunity as it has many lymph nodes

Q14. Types of stomach (5 marks)

A Monogastric stomach consists of a single strong muscular tube or sac.