Zoology Solved Past Paper 2nd year 2012 Karachi Board


i) Abductor muscles are Antagonistic to:
* Flexor muscles
* Protractor muscles
* Adductor muscles
* Rotator muscles

ii) Corpus Luteum secretes this hormone:
* Progesterone
* Insulin
* Oestrogen
* Luteinizing hormone

iii) the egg of hen is laid at this stage:
* Earty cleavage
* Morula
* Blastula
* Gastrula

iv) A fossil bird, having teeth, long tail, 20 vertebrae and wings, is called:
* Archaeopterix
* Kiwi
* Crow
* Duck

v) Urea is about 100,000 times less toxic than:
* Uric acid
* Oxalic acid
* Ammonia
*  Amino acid

vi) The number of pairs of Cranial nerves in Human is:
* 10
* 14
* 16

vii) The approximate number: of human genes on 23 pairs of chromosomes is:
* 10,000 to 15,000
* 20,000 to 25,000
* 30.000 to 35,000
* 45,000 to 50,000

viii) Microcephaly is caused due to:
* Malnutrition
* Genetic disorder
* Bacteria
* Fungi

ix) Follicle Stimulating Hormone (FSH) is produced by:
* Thyroid gland
* Adrenal gland
* Testis
* Pituitary gland

x) To construct rDNA, this is used as vector:
* Plasmid
* Virus”
* Mictochondria
* Vacuole

xi) The number of bones in the endo skeleton of the adult human is:
* 206
* 306
* 209
* 208

xii) This element is necessary 0 muscle contraction:
* Calcium
* Potassium
* Magnesium
* Sodium

xiii) The deficiency of Insulin may cause the disease:
* Diarrhoea
* High Blood Pressure
* Diabetes
* Anaemia .

xiv) Gonorrhoea is a sexual disease caused by:
* Treponema
* Neisseria
* Herpes simplex
* Entamoeba

xv) The connection between embryo and mother in relation to the exchange of food is;
* Oviduct
* Placenta
* Fallopian tube
Umblical cord

xvi) The excretory organs of earthworm are:
* Kidneys
* Gills
* Nephridia
* Flame cells

xvii) The change in Temperature is detected by:
* Thermo receptor
* Chemoreceptor
* Mechanoreceptor
* Photo receptor

xviii) Leishmania is transmitted into man’s body by the bite of:
* Mosquito
* Sand fly
* Trypanosoma
* Plasmodium


2.i) Define Joint and name various types of joints.
The site of union of bones is called joint. There may be two or more bones at one joint .
Types of Joints: Joints are- classified on the basis of amount of movement at that joint.
1- Immoveable joint
2- SlighUymoveable joint
3- Freely moveable joints.

ii) Explain Osmoregulation in Fresh water fish OR Marine water
Osmoregulation in Fresh water fish: Fresh water animals like, fishes have hypotonic body fluids than tile surrounding water. They remove excess water by passing large quantities of very dilute urine. It also secreted some essential ions in urine. .;rhis is regulated by actively absorbing selected ions from outside

Osmoregulation in Marine Animals: Marine animals like bony fishes
have hypotonic internal environment so, they are liable to lose water. The water conservation take place by actively drinking of water and excess salts are secreted through gills, along with water through special secretory cells



Some manne fishes like, sharks, and ray fishes have slightly hypertonic osmotic pressure of body fluid due to storing high
concentration of urea in their bodies. So, they are not facing problems of water loss. Excess salts are removed by salts glands in their rectum.

Marine invertebrates and some vertebrates like hag-fishes have isotonic body fluid, so·they dont have any osmoregulatory mechanism.

These animals are termed as osmoconformers.

iii) Describe the Posterior lobe of Pituitary gland.
Pituitary Gland lies in’ the brain attached to the base of hypothalamus by pituitary stalk or hypophyseal stalk. For this pituitary gland is also called as “Adrenal hypophysis.”
Two hormones are released from posterior lobe.
i) Oxytocin:
• It controls regression of uterus during parturation (child birth)
• It helps in ejection of milk from mammary gland during lactation.
ii) Vasopressin:
• It is also called Ant-diuretic honnone (ADH).
• It regulates amount of water’ the body by increasing the reabsorption of water from kidney.

iv) Write a note on DNA fingerprinting.
Ans: See on Page 409.

v) Define Aging and mention its causes.
Aging is the process of progressive deterioration in the structure and function of cell, tissue and organ of an organism as it grows older. It can be defined as negative physiological changes in our body. The science of aging is known as “qerontoloqy”.

In human people determine each others ages by identifying signs of
aging such as loss of hair pigmentation, skin wrinkles usually on face, development of pigment spot on face, generalized weakness, increase in weight due to fat, poor vision and gradual loss of memory, increase susceptibility to disease. Degeneration of organ and tissue may take place e.g. osteoporosis and osteoarthritis. There may be loss of elasticity


1-Genetic Origin: The experiment conducted by Leonard Hayflic and
Paul Moor Head indicated that we are geneticaiiy programmed to age. They cultured the normal embryonic human cell. They found that the cell divide upto fifty times than stop dividing and leading to death. It shows that normal cell have limited potential to divide themselve.
2-Gene Mutation: During the passage of time, it is noted that the capacity of DNA to repair themselve is lost. The DNA is-attacked by free radicals and denatured then lead to some gene mutation. This result in progressive inadequately functioning cell that causes aging. In elderly people the capacity to produce superoxide dismutase and catalase become defective which are necessary for breaking H202 a toxic metabolite and to eliminate free radical. As a result the free radical increases in the body thus the process of aging or cell death is faster. It is observed that regular meals, regular aerobic or low impact exercise, adequate sleep, aviodance of smoking may reduce the effect of aging and can prolong life by an average of 11 years

vi) Explain Parkinson’s OR Alzheimer’s disease.
Parkinson’s Disease: It is a brain disorder caused either by degeneration or damage to nerve tissue within the basal ganglia of the brain. The disease begins as a slight tremour of one hand, arm or leg which is worse at the time when limb is in rest. Later, the disease affects both the sides of the body and causes stiffness, weakness and trembling of muscles. The intellect remains unaffected until late in the disease although speech may become slow and hesitant.

Alzheimer’s Disease: It is a progressive degeneration of neurons of
brain (especially cerebral cortex and hippocampus). It causes dementia (loss of memory). The disease progresses in three broad stages. At first, the patient notices his forget fullness. In the second phase, there is a severe loss of memory particularly for recent events. The victim also becomes disoriented as to time or space, losing his way even on familiar streets. Anxiety increases with sudden changes in mood. In the third stage, the patient becomes severely disoriented and may suffer from symptoms of psychosis such as hallucinations (hearing voices or seeing faces when no one is there) and paranoid delusions (A fixed,irrational idea not shared by others and not responding to reasoned arguments.

vii) Write a note on Arthritis.
It is a condition in which a joint becomes swollen, painful and immovable. It may be hereditary, may be due to a viral infection or due to an injury or sometime only due to aging. In this disease the smooth and flexible cartilage between the bones of a joint is denatured by the deposits of calcium, which make the cartilages hard. The joints become very stiff and hard to move, and the person becomes crippled. The only remedy is rep!acement of the affected joints by artificial joints made up of rubber and plastic. Artificial joints are often used to replace stiff hip and knee joints.

viii) Define Neuron and give the names of different types of Neurons.
“Neurons are the structural and functional unit of nervous s stem. They are exitable cells of which nervous tissue is made.·

A neuron consists of:
1) Cell body or soma.
2) Dendrites
3) Axon

‘Neurons are classified on following ‘bases.

1- Structural basis.
2- Number of cell processes basis.
3- Physiological basis.

ix) Name the diagram given below as well as the parts market in it.



A- Nucleus
8- Cilia
C- Excretory tubule
D- Flame – Cell System of Planaria

x) Write a note on Regeneration.
“The ability to regain or recover lost part or injured part of the body is called as “regeneration”. It is more common in invertebrates than vertebrates. Simplel organisms have greater power of regeneration than advance organism.
1. The sponges have greater power of regeneration.
2. In starfish or hydra when chopped into many pieces, each part can regenerate into eornptete orqamsrn.
3. In arthropods the appendages can be regenerated
4. Salamanders and lizards ‘can regenerate their tails.
5. In birds and mammals regeneration is limited to the small wound by the formation of new tissue or scar. So the healing of wound and fracture is example of regeneration.
6. In earthworm, if head is removed a new head is regenerated

xi) Explain the process of Oogenesis.
The process of production of ova (eggs) from the germ cells in the female gonads (the ovaries) called oogenesis



Germ cells in the ovary divides mitotically to form oogonia. The oogania undergo first meiotic division and develop into primary oocyte and one polar body, which contain 2N but replicated double structured chromosome: Then the primary oocyte and polar body undergoes second meitotic division and develops into secondary oocyte and a polar body from primary oocyte and, two polar bodies form polar body found in 1st meiotic divition. The secondary oocyte is N i.e, it contain single structured chromosomes. Thus there are total 3 polar bodies are formed during this process. The process is completed in one month.

xii) Differentiate Renewable and Non-renewable resources of Environment.
Ans: See on Page 407.

xiii) Write a note on Lithotripsy.
Ans: See on Page 406. .

xiv) Mention Hydrostatic skeleton with examples.
It is a fluid filled gastrovascular cavity which act as hydrostatic sKeleton and give support and resistance to muscles contraction to cause proper motility.
Example: This type of skeleton is found in Annelids (earthworm), Cnidarian (Hydra) and other soft bodied invertebrates (Echinoderms, sea anemone).

xv) Write a note on Placenta.
Ans: See on Page # 419.

xvi) Explain ‘Reflex action’.
“This is a rapid automatic involuntry response to a stimulus. It is not under the control of the will, not controlled by brain.”
1. Each time a physician hits the knee tendon the patient extends forward his leg with a jerk
2. If one hand unconsiously touches any hot substances, it eventually reflects back from that substance. It is due to reflex action in which brain is not involved. It is sub-cortical response because if brain has to involve it will take more time for taking  any decission and realizing this fact that the hand is getting burnt. So, this is an every day life example of reflex action.


3. Describe the Structure of Nephron and explain the regulatory
functions of Kidney.
Ans: See on Page # 427.

4. What is Menstrual cycle? Describe the various phases and the changes occurring in each phase.
Ans: See on Page 411.

OR What is Behaviour? Explain “Learning Behaviour” and crlso state its various types.
Behaviour: The activities of animals in response to enviromental or physiological necessaties is called “BEHAVIOUR”.
Learned Behaviours: It refers to a more or less permanent change in behaviour, which occurs as a result of experience. It differs from the innate behaviour in being acquired or modified from experience. It permits an animal to adopt quickly to the changing circumstances.
There are different types of learned behaviour, such as habituation,
imprinting, classic conditioning, operant conditioning, latent learning and insight learning.
Habituation: It is the type of learned behaviour in which animal stops responding to a repeated stimulus, which is neither beneficial nor harmful. It is the simplest type of learned behaviour. For example, birds feeding along a road side or perched on pole or tree along a busy highway habituate to the cars and buses passing at a few feet; city dweller people habituate to night-time traffic sounds; and country dwellers to the choruses of crickets and frogs.
Imprinting: It occurs during very early stage in the life of birds and
mammals. During this period called sensitive period, the animal is primed to learn a specific information, which is then incorporated into an innate behaviour. Lorenz in 1930· found that ducklings follow the first large, noisy, moving object they see after hatching. There after, they will continue to follow the same object even if their true mother is there.
Classic Conditioning: In classic conditioning or association conditioning an animal learns to give a response to an irrelevant stimulus. It is associated with reward or punishment. Pavlov in 1902 performed classic experiment on digestion in dG~s. HI::: first placed drieu meat powder into a dog’s mouth causing release of saliva. There after he rang a bell just before presenting meat poWder. The process was repeated several time. Later, the dog started salivating at ringing of the bell rather than seeing the meat.
Operant conditioning (trial and error learning): In this kind of learning an animal learns to associa:e one of its behaviour (such as pushing a lever etc) to receive an award or punishment. Skinner developed a box called Skinner box for his experiments on conditioning with hungry pigeons or mice. Inside the box, there was lever which operated a food supply. When the lever was pressed by the animal, a sample of food was delivered. After several accidental incidents of pressing the lever, the hungry animals learnt to press the lever at the time of their hunger.
Latent Learning: The ability of rats to find their way in underground tunnels is very remarkable. If a rat is placed in a maze, it was observed that using its natural ability, the rat very soon finds its way out of the maze without b:.:ing rewarded at the end of the maze. So this type of learning which is not associated with a particular stimulus and is not normally rewarded or punished, but is utilized in different situation at a later time is called latent leaming.
Insight Learning (Reasoning): Solving a problem without trial pnd error learning is called insight learning. It is the most developed form of learning behaviour. The classic experiment, which demonstrated jnsight learning was performed on chimpanzees. Presented with a bunch of bananas hanging too high to reach and few boxes, some chimpanzees piled up boxes to make a stand for themselves to reach the bananas.

5. What· is Evolution? Discuss Darwin’s Theory of Natural Selection. List the objections to this theory.
Ans: See on Page # 415.

Posted on January 4, 2016 in 2nd Year 2012 Karachi Board Past Papers

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