Zoology Solved Past Paper 2nd year 2013 Karachi Board

solved MCQs Pass Papar 2013 Zoology

solved MCQs Pass Papar 2013 Zoology

solved MCQs Pass Papar 2013 Zoology

solved MCQs Pass Papar 2013 Zoology

SECTION ‘B’ (SHORT – ANSWER QUESTIONS)

2.i) Differentiate between Nervous ‘::o-ordination & Chemical C.) ordination
Ans See on Page # 409.

ii) Write a note on Latent learning OR ‘nsiqht learning
Latent Learning: A type of learning . .ch ISno associa .WI a particular stimulus, or in” response to a .’ , ular =trmulus and s . t
normally rewarced or reinforced but it is uu. – In different s tuation at
a time IScalled as atent learning. Example: The ability of rats to move in ma e ha been th ‘ghiy investigated. The earn within 2 to 3 days maz ~ wrh hundreds . b Wl alleys. Although the rat may be rewarded at t v= end, they lea to rul equally quickly to the maze with expe .ence f),Scas, hE-If d some food at the end 0 maze, they could use the’ ex; r nce 0 ,el ,\ learning in other males to acheive some reward t a ater ime. Insight Learning: Insight learning IS the ability to . 0 ectly plan a response to a new situation. In this animals de rves new behaviours 0 solution to problem by thinking about them Previous specific expenments are not nvolved.
Example: It is most readily demontrate n chimpanzee Suppose a chimpanzee IS placed In a ~arge cage contamnq some boxes. Bananas have been hung from .ne top of the cage. and a e ou, of chimpanze’s reach.

At first chimpanzee begins to jump for the bananas, but it can not reach them, rater instead of jumping, he gather boxes, stacks them and crawls up a boxes reaching the bananas.
This is an example of insight learning in which the chimpanzee solve the problem to reach the bananas by thinking over it and not in the light of previous experiments. The chimpanzee’s concept was that added height would allow him to reach to bananas.

iii) Name the various types of Asexual reproduction in animals with examples.
The common type of asexual reproduction in animal is fission, budding, regenration, parthenogenesis fragmantation and’ cloning.
(i) Fission
(ii) Budding
(iii) Regeneration
(iv) Parthenoqenesls
(v) Fragmentation
(vi) Cloning

i- Fission: It is a simplest form of asexual reproduction that involve splitting of parent cell into the independent daughter cells.
Example: It takes place in algae, fungi and certain protozoans liMe amoeba, plamoduim, monocysts.
ii- Budding: It is type of asexual reproduction in which new organism is produce as a bud or out growth on an organism.
Example: In hydra bud forms laterally which separate from parent body and grows into a new individual. .
lll- Regeneration (Autotomy): This is a process of regrowing of missing part which is lost accidentaly or when cut in laboratory. In regenration the mature animals divides into two half each half reforms its lost part and become a complete animal this type of
reproduction is commonly seen in platyhelminthes.
Example: Planaria, earth worm, echinoderms.
iv- Parthenogenesis: It is the process in which egg cell develop into adult without fertilization. Only one partner is needed to produce
individual just like asexual reproduction.
Example: It is found in insects the arthropodes, honey bees, ants and wasps.
v- Fragmentation: By this. process parent body split off and grow into new complete individual.
Example: sponge.
vi- Cloning: It is uncommon but new technique of reproduction the formation of new individual requires only one unfertilized egg whose nucleus is replaced by diploid nucleus of somatic cell.
Example: The first cloned sheep is called “Dolly”.

iv) Write a note on Acid rain.
Ans: See on Page # 406.

v) Give any two evidences in support of Evolution.
1- Evidence from Classification: All the members of a family has resemblance, class. order genus i.e., they may have evolved from some common ancestor.
2- Evidence from Homology: Resemblance or similarities of the structures of the organism 8.9 fore limbs of birds, dog, whale, bat, man etc.

vi) Name any four Viral diseases & modes of their transmission.

Viral diseases & modes

Viral diseases & modes

vii) Describe Osmoregulation in Terrestrial animals.
Ans: See on Page 406.

viii) Write a note on Exoskeleton.
The ectodermal cells of animal body secrete some material which becomes hard, it is inert and non-living. It provide attachement to internal muscles. It has two layer.
a) The Epicuticle: Out.v layer r .ade up of waxy lipoprotein.
b) The Procuticle: inner ‘.-l/er made up of chitin, polysaccharides protein and calcuim Cdl oonate.
Advantages:
It provides surface for attachement of muscles.
It gives protection to animal against its enemies.
Disadvantages: ,
It retards steady qrowth of animal.
When exoskeleton shed, and animal start secreting another exoskeleton, this entire period is harmful to this animal. The
process is called Ecdysis.

ix) Define Receptors, State the different types of receptors with
their functions.
Ans: See on Page # 419..

x) Name the parts marked in the diagram

figure

figure

xi) State the role of Honnones in the working of Kidneys.
Structure of kidneys is adapted to the natural habitat of animals.
The permeability of the walls of the collecting ducts to water is regulated by antidiuretic hormone (ADH) or vasopressin. It is secreted by posterior pituitary gland in response to increased osmotic pressure of the blood (i,e. dehydrating condition). Due to the presence of ADH. the reabsorption of water in the collecting duct is increased.
The concentration of sodium ions in the body fluids is controlled by another hormone called aldosterone secreted by adrenal cortex. It increases the reabsorption of sodium ions in the nephron. Similarly the concentration of calcium ions in the blood is controlled by parathormone secreted by parathyroid gland. It increases the reabsorption of clacium ions in nephron.

xii) Differentiate between Striated and Unstriated muscles.
Striated Muscles: These are the muscles associated with the bones and enable your skeleton to move. Skeletal muscles are voluntary in function. They can contract strongly and rapidly but fatigue quickly. These muscles are made up of protein filaments. Under the microscope, skeletal muscle cells look striped, hence they are also called striated muscles.
Non-striated Muscles: Non-striated are also called smooth muscles are structurally the simplest of all muscle types. They consist of long spindle shaped uni-nucleated cells that are usually arranged in sheets that surround the body’s hollow organs. They are involuntary that is their contraction is not under the conscious control of animal itself. instead they are automatic being controlled by autonomic nervous system.

xiii) Write a note on AIDS.
It is caused by HIV ( human immono deficiency virus). It mainly spreads through sexual contact. It destroys the immune system and expose the person to all type of infections. It also spreads through unscreened blood transfusion. Infected or reuse syringe needle or infected shaving blades. Newborn also infected through placenta of RIV infected mother

figure

figure

xiv) Define Joint. Draw a labelled diagram of Ball and Socket joint.
The site of union of bones is called joint.
Ball and Socket Joint: The joints which allow movement in several directions. They provide maximum flexibility.
Example: Hip and Shoulder joints.

xv) Differentiate between Innate and learned behaviour.
Innate behaviours are automatic, pre-programmed, genetically determined, stereotype activities. which do not involve any learning while learned behaviour refers to a more or less permanent change in behaviour, which occurs as a result of experience.

Most instincts of innate behaviour are adaptive in nature ereas learned behaviour permits an animal to adopt quickly to the
changing circumstances,
Innate t)ehaviour can be categorized into following types: Kinases; Taxes; eflexes and fixed action patterns while learned behaviour is categorized into habituation, imprinting, classic conditioning, operant conditioning, latent learning and insight learning.

xvi) Describe Locomotion in Jelly fish.
A jelly fish has an umbrella shaped body which flaats freely on water or swims by contracting its muscle cells forcing the water powerfully out of its mouth and umbrella to create a jet propulsion effect. The jelly fish moves in jerks in the direction opposite to the expelled water.

SECTION ‘C’ (DETAILED – ANSWER QUESTIONS)

3. Describe the structure of Skeletal. muscles and explain the Mechanism of their contraction. Draw Labelled diagram of Skeletal muscles.
The type of muscle present in skeleton, striated in appearence and voluntary in action is called skeletal muscle. Structuraf and functional unit of muscle is muscle fibre which is complete cell embeded in connective tissue matrix. Composition of Muscle tfibre: Muscle fibre is 1 – 40 mm in length and is about 10 – 100 micrometer in diameter. It is composed offollowing.
1- Sarcolemma: It is cell membrane of muscle fibre that surround it.
2- Sarcoplasm: It is matrix present in muscle fibre just like cytoplasm. It contain large amount of .glycogen and o~en carring Protein called “myoqlobin”, which is red pigment.
3- Sarcoplasmic Reticulum: Endoplasmic reticulum of muscles fibres.
4- Nerve Supply: Each muscle fibre is innervated by one nerve ending in the centre.
5- Myofibrils: These are longitudinal threads of muscles fibres. That
run in parallel fashion and extend entire iength of cell. It is about 1 – 2 micrometer in diameter .•
6- Nucleus: Each muscle fibre contains many large oval nuclei.
7- Sarcomere: Myofibril consist of contractile unit called sarcomere. It has dark A and light I band. It is a portion of myofibril between two
successive Z lines.
Skeletal Muscle: Skeletal muscle has three parts i.e., Origin: Origin is end of muscle which is attached to bone with short tendon. It remains fixed during muscle contraction.
Belly: Belly is thick part of muscle between origin and insertion. It is
main flesh of muscle.
Insertion: It is the end of muscle which is attached to bone with.a long tendon. It oves the bone wnen muscle contracts. Movement occurs at insertion of muscle not at origin of muscle.
Tendon: Tendons are thick bands of connective tissue which attach
muscle to bones. They are non-elastic. Tendon at insertion IS longer than tendon at origin.
ligament: They are thin bands of connective tissue which attach bones to each other at joints. They are slightly elastic

CONTRACTION OF MUSCLE

CONTRACTION OF MUSCLE

Mechanism: The muscle fibres contract when they receive impulses from motor neurons. Mechanism is as follows:

The nwcharism

The nwcharism

1- Bridges of myosin filaments gets attached with actin filament.
2- Actomyosin complex is formed.
3- Bridges contract simultaneously.
4- These contraction cause thin filaments to slide under thick filament.
S- Bridges then detaches from myosin and reattached themselves to
new site on it.
6- Procedure repeats again and again to cause contractions.
Effects: Following effects are produced.
1- I bands and I-j zone become shorter.
2- Dark region of A band become longer.
3- Length of A band remains unchanged. (remains constant) \
4- Z-disk,come closer thus length of sarcomere shorter.

The rate of contraction of muscle depend upon the number of attachement of bridges. Normally bridge complete their cycle of activity 100-500 times per minute.

Energy For Muscle Contraction:
1- Energy for muscle contraction is derived from ATP (Adenosine tri phosphate) stored in mitochondia, so muscle cells have lot of mitochondia. ‘
2- Further energy is derived from “creatine phosphate” which comes from break down of glycogen by respiratory chain. It produce lactic acid whose accumulation cause muscle fatigue.
3- Calcium ion also play active role in muscle contraction.

4. How do Homiotherms maintain their body temperature during hot & cold seasons?

Homeotherrns are generally known as warm-blooded animals (Mammals). They have constant body temperature. They can maintain their body temperature despite of change in atmospheric temperature. The normal range of temperature in mammals is 36-38°C. The regulatory mechanism includes both loss and conservation of heat. In some mammals temperature regulate by specialized fat called brown fat, found in the neck and between the shoulders responsible for rapid heat production.
A- Mechanism of Thermoregulation in Cold Temprature: This include both means i.e, physiological and behavioural.
1- Physiological Mechanism:
(a) Non Shivering Thermogenesis:
i) Erection of Hair: Hairs are raised to an almost vertical position due to the contraction of erector.pili muscles in the skin. In furry animals, the hair in vertical position can trap a thick layer of stationary air next to the skin. Due to this heat loss from the skin is reduced.
ii) Reduction in blood flow towards skin: The heat is transported by the blood all round in the body. In cold temperature, the narrowing of the arteriole or vaso-constriction occurs so the lesser blood is supplied towards the body surface ·to conserve the body heal. This is more marked in the limbs than in the rest of the body.
iii) Subcutaneous fat accumulation: In mammals, fat is stored in adipose tissue below the skin. It is a bad heat conductor so it serves as a means of conserving heat. This is particularly very important for the survival of aquatic mammals like seals, whales, walrus, etc. However, in terrestrial rr-ammals which remain active in cooler season, fats are primarily stored as reserve food.
(b) Shivering thermogenesis: In cold condition, the muscle tone, initially under nervous control, tend to rise. If the cold continues shiverinq begins which generate heat in muscles. Under persistant cooler conditions, the basal metabolic rate (BMR) is raised in short term by the secretion of hormone adrenaline and in longer term by the secretion of another hormone, thyroxine. (T4) from thyroid gland)
2. Behavioural mechanism: Behavioural mechanisms include moving to a warmer location, huddling close together with other individuals; in humans putting on additional clothes.
B- Mechanism of Thermoregulation in Hot Temprature: It includes both physiological and behavioural mechanisms.
1- Physiological Mechanism: Few of these mechanisms include .
Loweirng the hair growth which reduce the insulating effect.
Reduction in subcutaneous fat.
Evaporative cooling effect by means of secretion of sweat from skin Vasodialation of arterioles of skin promote heat loss by flowing of blood to the skin .
Few animals losing heat from mouth, tongue and respiratory passage .
1- Low metabolic rate also help in reduction of heat.
2- Behavioural Mechanism: It involves migration or moving of animals to a cooler location, use of thin clothes etc.

OR Define Organic evolution. Describe lamack’s theory and point out the objections raised against the theory.
Organic evolution: The word ‘evolution’ refers to the gradual development of something i.e. evolution of earth, evolution of man, evolution of plants and so on and so forth. The evolution with reference to plants or animal or both is referred to as organic evolution. Broadly, evolution can be said to be the development of an entity in the course of time through gradual sequence of changes from simple to complex ate.
Organic evolution is the gradual and orderly development of living organism from simple and unorganized form to complex and organized form.
Theories of Evolution: The most profound theories about evolution are,
1- Theory of Specjal Creation
2- Theory of Acquired Characters (Lamark’s Theory)
3- Germinal Continuity Theory
4- Theory of Natural Selection (Darwin’sTheory)
5- Mulation Theory
lamack’s Theory: Jean Baptiste de Lamarck (1744-1829) was a great French Zoologist and a pioneer evolutionist of the pre-Darwin penod. In his book Philosphie Zoologique pupllshed in 1809 elaborated a new theory of organic evolution based on the principle of use and disuse of organs. Lamarckism (Lamarckian Theory) is now considered as Inheritance of acquired characters.
His theory was based on following postulates:
(i) Effects of environment.
(ii) Use and disuse of organs.
(iii) Inheritance of acquired characters.

(i) Effects of Environment: Lamarck believed that evolution of new
types takes place by the effect of the environment, when some animals under changed condition of environment require new needs and as such acquire new characters (new organs) to better meet with the changed situation of food habit, physiology or shelter seeking.
(ii) Use or Disuse or Organs: In order to satisfy these new needs ,organisms use some organs persistently and disuse others. So the efforts of an organ and disuse results in its degeneration and ul mate disappearance. Lamarck believed that the accumulation of such small changes through successive generations promote the origin of new organs or characters, which are transmitted to its offspring in the next generation. This is called Inheritance of acquired characters.
(iii) Inheritance of Acquired Characters: Lamarck believed that once made, these adaptations called acquired characteristics are transmitted from generation to generation .So new generations show new characters with the development of some new organs on the basis of use and disuse of organs.
Lamarck cited numerous examples to illustrate anc support his evolution theory.
Evolution of Giraffe: The ancestors of giraffe were horse like and lived in Africa having enough graph and herbage to eat, when forced to £raze upon foliage leaves of trees, thus by continuous effort of stretching the neck and fore-limbs increased in each generation to reach this food, they progressively achieved enormously elongated fcre-limbs and neck. Evolution of Snake: In order to escape from attacks of many mammals, the lizard-like ancestors and snakes deveioped the habit of gliding, over the ground and creeping through narrow fissures and holes. As a result, their bodies become elongated and limbs disappeared due to their disuse, after a large number of generations  With these he also gave other examples like: Evolution of Kiwi, Evolution of foot of modem horse, Evolution of webbed feet of duck, Evolution of loss of teeth in whale, etc. Objections on Lamarckian Theory: On the three factors necessary for Lamarckian theory, there is no much dispute about the first two viz. the effect of the changing environmental factors and the effect of use and disuse in evolution process unless the third factor i.e. the imheritance of acquired characters, is operative.
The transmission of acquired characters is crucial factor to the theory given by Lamarck. Many objections were put forth against this hypothesis.

daigram

daigram

1. Mutilations as a result of accidents or diseases are not inherited.
2. Boring of holes in ears and nose in mothers is not inherited in new born child.
3. Many human families observe circumcision ceremony in infant males since thousand of years, despite that every baby boy in each generation is born with ‘ a fore-skin. This proves that acquired characters are not inherited.
4. The greatest set back to Lamarckism was Weismann’s theory of germinal continulty in 1892. He was a German BIologist.

5. Define Gastrulation. Explain the development of chick up to the formation of three germinals layers.
The process of gastrula formation is called GASTRULATION.
During this process, the cell division, cell migration and rearrangement at definite location of embryo take place. These cells begin to differentiate into definite layers known as the ectoderm, the mesoderm and the endoderm. Fate of the Three Germinal Layers: After the gastrulation the embryo become triploblastic having three germinal layers.

1- Ectoderm
2- Mesoderm
3- Endoderm

daigram

daigram

1- Ectoderm: It is the extemal covering of gastrul. It give rise to
i. Epidermis or skin.
ii. Nervous system
iii. Cutaneous glands
iv. Sensory parts (Lens, retina, iris, nasal, epithelium, membranous Labryinth)
v. Enamel of teeth.
vi. Cloaca or proctodaeum.
2- b: It lies below the ectocerru. It gives rise to,
i. All body muscles
ii. Connective tissues
iii.Dermis
iv.Peritonial membrane
v.Heart, vascular system and blood
vi.Skeleton i.e, bone, ligaments and cartilage

 

Posted on January 4, 2016 in 2nd Year 2013 Karachi Board Past Papers

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