GS notes on "BLOOD"

Blood

The main functions of blood are to transport oxygen, carbon dioxide, water, nutrients, hormones and waste around the body. Blood also fights infection and regulates temperature. 

Composition of blood:

1. Plasma constitutes for about 54% of our blood. 92% of it is water. 

2. White blood cells and platelets constitute for about 1% of our blood. 

3. Red blood cells constitute for about 45% of our blood.

Circulatory System 

Circulation of Blood through the heart:


Systemic Vein ⇨ Sinus Venosus ⇨ Right Auricle ⇨ Right Ventricle ⇨ Pulmonary Artery ⇨ Lungs ⇨ Pulmonary Vein ⇨ Left Auricle ⇨ Left Ventricle ⇨ Trunchus Arteriosus ⇨ Systemic Circulation

Open circulatory systems allow the blood flow out of the vessels before returning to the heart via ostia. (no veins involved)E.g. insects

• Closed circulatory systems don’t allow the blood to leave the blood vessels E.g. humans advantages include faster and controlled delivery of oxygen and nutrients which allow for longer periods of activity.

Important Points: 

➧Aorta
The largest artery in the body. It carries oxygen-rich blood away from the heart to vessels that reach the rest of the body.
➧Atria
The chambers of the heart, to which the blood returns from the circulation.
➧Capillaries
The smallest of the body's blood vessels. Oxygen and glucose pass through capillary walls and enter the cells. Waste products such as carbon dioxide pass back from the cells into the blood through capillaries.
➧Cardiac Valves (Heart Valves)
Any of the four heart valves that regulate the flow of blood through the chambers of the heart.
➧Deoxygenated Blood -> Oxygen-poor blood.
➧Heart Ventricles
The lower right and left chambers of the heart.
➧Interventricular Septum
Interventricular septum is the stout wall separating the lower chambers (the ventricles) of the heart from one another.
➧Lungs
One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.
➧Myocardium
The muscular substance of the heart; the middle of the three layers forming the outer wall of the human heart.
➧Oxygenated Blood -> Oxygen-rich blood.
➧Pulmonary Artery
The pulmonary artery and its branches deliver blood rich in carbon dioxide (and lacking in oxygen) to the capillaries that surround the air sacs.
➧Pulmonary Circulation
The circulation of the blood through the lungs.
➧Pulmonary Veins
The veins that return the oxygenated blood from the lungs to the left atrium of the heart.
➧Superior Vena Cava
The large vein that carries blood from the head, neck, arms, and chest to the heart.
➧Vena Cava
A large vein which returns blood from the head, neck and extremities to the heart.
➧Endothelium is the innermost layer of blood vessels that consists of just a single layer of cells. 

➧Veins are blood vessels that carry blood to the heart in an even flow. They have thin walls large lumens and valves. 

• The human circulatory system consists of two circuits systemic and pulmonary. 

• The coronary artery carries blood to the heart muscle from the aorta. (coronary vein) 

• The hepatic artery carries blood to the liver. (hepatic vein)

• The renal arteries carry blood to the kidneys. (renal veins) 

• The mesenteric arteries carry blood to the small and large intestines.

• The carotid arteries supply blood to the head. (jugular veins) 

• The subclavian arteries supply blood to the arms. (subclavian veins)

• The iliac arteries carry blood to the legs. (iliac veins)

• A portal system is a network of capillaries in one organ or tissue joined to another network of capillaries in another organ or tissue via a vein or veins. 

• A pulse is the alternate contraction and relaxation of an artery as blood passes through it.

• Blood pressure is the force blood exerts on the walls of blood vessels. 

• A sphygmomanometer is used for measuring blood pressure(normally 120/80 mmHg) 

• Atherosclerosis is the hardening of artery walls due to a build-up of fatty deposits.

• Smoking causes heart rate and blood pressure to increase. Diet high in saturated fats increase blood pressure and atherosclerosis. Exercise helps lower blood pressure. 

GS notes on "BLOOD"

BLOOD GROUP

➽BLOOD DONER AND RECEIVER

➠BLOOD TYPES ARE INHERITED

➧Blood Groupings

• Father of Blood Grouping : Karl Landsteiner
• He discovered A, B and O blood groups
• Decastello and Sturle discovered AB blood groups

Blood Group	Can donate to	Can receive from
A	A,AB	A,O
B	B,AB	B,O
AB	AB	A,B,AB,O
O	A, B, AB, O	O

➧RH factor

• It is a blood antigen found in RBC
• A person can be Rh+ or Rh- depending upon the presence of Rh factor in RBC
• Rh+ can receive blood from both Rh+ and Rh- but Rh- can receive blood only from Rh- only

Blood transfusion techniques was developed by Dr. James Blundell.

GS notes on "BLOOD"

Today's post contain all DISEASES related to Blood.

DISEASE

➽Hematoma: A collection of blood inside the body tissues. Internal bleeding often causes a hematoma.

➽Leukemia: A form of blood cancer, in which white blood cells multiply abnormally and circulate through the blood. The excessive large numbers of white cells deposit in the body's tissues, causing damage.

➽Multiple myeloma: A form of blood cancer of plasma cells similar to leukemia. Anemia, kidney failure and high blood calcium levels are common in multiple myeloma.

➽Lymphoma: A form of blood cancer, in which white blood cells multiply abnormally inside lymph nodes and other tissues. The enlarging tissues, and disruption of blood's functions, can eventually cause organ failure.

➽Anemia: An abnormally low number of red blood cells in the blood. Fatigue and breathlessness can result, although anemia often causes no noticeable symptoms.

➽Hemochromatosis: A disorder causing excessive levels of iron in the blood. The iron deposits in the liver, pancreas and other organs, causing liver problems and diabetes.

➽Sickle cell disease: A genetic condition in which red blood cells periodically lose their proper shape (appearing like sickles, rather than discs). The deformed blood cells deposit in tissues, causing pain and organ damage.

➽Bacteremia: Bacterial infection of the blood. Blood infections are serious, and often require hospitalization and continuous antibiotic infusion into the veins.

➽Malaria: Infection of red blood cells by Plasmodium, a parasite transmitted by mosquitos. Malaria causes episodic fevers, chills, and potentially organ damage.

➽Thrombocytopenia: Abnormally low numbers of platelets in the blood. Severe thrombocytopenia may lead to bleeding.

➽Leukopenia: Abnormally low numbers of white blood cells in the blood. Leukopenia can result in difficulty fighting infections.

GS notes on "Human Brain"

HUMAN BRAIN

The brain is the most complex part of the human body. This three-pound organ is the seat of intelligence, interpreter of the senses, initiator of body movement, and controller of behavior.

The brain can be divided into three basic units: 

1. The forebrain, 
2. The midbrain, and 
3. The hindbrain

The forebrain is the largest and main thinking part of the brain. It has regions which receive sensory impulses from various receptors. Separate areas of the fore-brain are specialised for hearing, smell, sight and so on.

• Cerebrum

The Midbrain connects the forebrain to the hindbrain. 

• Hypothalamous

The hindbrain controls the body’s vital functions such as respiration and heart rate.

• Pons
• Medulla
• Cerebellum

➽CEREBRUM [Largest part of the human brain]

• It sits at the topmost part of the brain. 
• It is the source of intellectual activities. 
• It holds your memories, allows you to plan, enables you to imagine and think. 
• It allows you to recognize friends, read books, and play games.
• It controls the voluntary motor actions.
• It is the seat of learning and memory.
• It is the site of sensory perceptions; like tactile and auditory perceptions.
• It is divided into two hemispheres; called cerebral hemispheres.

➽HYPOTHALAMUS 

• It lies at the base of the cerebrum. 
• It controls sleep and wake cycle (circadian rhythm) of the body. 
• It also controls the urges for eating and drinking.
• It gets the adrenaline flowing during a test or job interview. 

➽CEREBELLUM 

• It lies below the cerebrum and at the back of the whole structure.
• It coordinates the motor functions. 
• It is responsible for precision of voluntary actions and maintaining the posture and balance of the body.
• Example: When you are riding your bicycle; the perfect coordination between your pedaling and steering control is achieved by the cerebellum.

➽MEDULLA 

• It forms the brain stem; along with the pons. 
• It lies at the base of the brain and continues into the spinal cord. 
• It controls various involuntary functions 
• Example : heart beat, respiration, size of the pupil, blood pressure, salivation and vomiting etc.

➽THALAMUS

• a major clearinghouse for information going to and from the spinal cord and the cerebrum.

Cerebrospinal fluid (CSF) is a watery fluid that circulates through the brain's ventricles (cavities or hollow spaces) and around the surface of the brain and spinal cord. 

NEURON

Neurons are the core components of the brain and spinal cord of the central nervous system (CNS).

Functions of the three parts of a neuron:

➨Axon: It conducts messages away from the cell body.

➨Dendrite: It receives information from axon of another cell and conducts the messages towards the cell body.
➨Cell body: It contains nucleus, mitochondria, and other organelles. It is mainly concerned with the maintenance and growth.

SYNAPSE : It is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron.

GA Study Notes On Clouds

CLOUDS

Cloud is a mass of minute water droplets or tiny crystals of ice formed by the condensation of the water vapour in free air at considerable elevations. As the clouds are formed at some height over the surface of the earth, they take various shapes. 

According to their height, expanse, density, and transparency or opaqueness clouds are grouped under four types: (i) cirrus; (ii) cumulus; (iii) stratus; (iv) nimbus

➤➤Cirrus

➤➤Cirrus clouds are formed at high altitudes (8,000 - 12,000m). 
➤➤Cirrus clouds are the highest of all clouds and are composed entirely of ice crystals.
➤➤Cirrus clouds are precipitating clouds, although the ice crystals evaporate high 
       above the earth’s surface.
➤➤They are thin and detached clouds having a feathery appearance. They are always white in colour.


➤➤Cumulus 
➤➤They are generally formed at a height of 4,000 -7,000 m.
➤➤Cumulus clouds look like cotton wool. 
 ➤➤They exist in patches and can be seen scattered here and there and have a flat base.
➤➤They are Often called “fair-weather” clouds.
➤➤ cumulus clouds are common over land on sunny days, when the sun heats the land creating thermal convection currents.Each thermal is distinct, and, consequently, each cumulus cloud is a distinct puff

➤➤Stratus
➤➤Stratus clouds are the lowest forming and are often called fog or mists when they are earth-bound.
➤➤As their name implies, these are layered clouds covering large portions of the sky. 
➤➤These clouds are generally formed either due to loss of heat or the mixing of air masses with different temperatures.Stratus clouds are formed when a large air mass cools at the same time.

➤➤Nimbus
➤➤Nimbus clouds are black or dark gray.
➤➤ They form at middle levels or very near to the surface of the earth.
➤➤ These are extremely dense and opaque to the rays of the sun.
➤➤ Nimbus clouds are shapeless masses of thick vapour.

➤➤Most of our names for clouds come from Latin and are usually a combination of the following prefixes and suffixes:

➤➤Stratus/strato = flat/layered and smooth
➤➤Cumulus/cumulo = heaped up/puffy, like cauliflower
➤➤Cirrus/cirro = High up/wispy
➤➤Alto = Medium level
➤➤Nimbus/Nimbo = Rain-bearing cloud

We can combine these names and can build up an idea of any cloud's character. For example, if we combine nimbus and stratus we get 'nimbostratus' - a cloud which is flat and layered and has the potential for rain.

➤➤A combination of these four basic types can give rise to the following types of clouds:
➤➤High clouds – cirrus, cirrostratus, cirrocumulus;
➤➤Middle clouds – altostratus and altocumulus;
➤➤Low clouds – stratocumulus and nimbostratus;

➤➤ clouds with extensive vertical development – cumulus and cumulonimbus

Zoology Questions

Zoology Questions and Answers for Interview

1. Which of the following organism is iteroparous ?
(A) Pacific salmon fish 
(B) Virus
(C) Bacteria 
(D) Humans
Ans : (D)

2. A micromutation is—
(A) Polyploidy
(B) Addition of chromosome
(C) Deletion of chromosome
(D) Change in gene frequency
Ans : (D)

3. The limited period of sexual receptivity that occurs around the time of ovulation in all female mammals except humans is called—
(A) Menstruation 
(B) Luteinization
(C) Oogenesis 
(D) Estrus
Ans : (D)

4. The rate and force of the heart-beat, and the secretion of digestive glands are controlled by—
(A) Central nervous system
(B) Spinal nerves
(C) Cranial nerves
(D) Autonomic nervous system
Ans : (D)

5. Glycosidic bond is broken during digestion of—
(A) Protein 
(B) Starch
(C) Lipid 
(D) All the above
Ans : (B)

6. Postganglionic parasympathetic fibres are—
(A) Adrenergic 
(B) Cholinergic
(C) Both (A) and (B) 
(D) None of these
Ans : (B)

7. In glycosuria disorder, urine contains—
(A) Amino acid 
(B) Inorganic ions
(C) Glucose 
(D) Epithelial cells
Ans : (C)

8. Mammillary bodies are attached to the ventral side of—
(A) Olfactory lobe
(B) Cerebral hemisphere
(C) Diencephalon
(D) Medulla oblongata
Ans : (C)

9. Argentaffin cells are associated with—
(A) Tumour 
(B) Heart muscle
(C) Pericardium 
(D) Pelvis of kidney
Ans : (A)

10. Sweating on palm and sole due to psychic stimuli is called—
(A) Bradykinin 
(B) Blushing
(C) Cold sweat 
(D) None of these
Ans : (C)

11. Capsule of Tenon is associated with—
(A) Eyeball 
(B) Brain
(C) Skin 
(D) Kidney
Ans : (A)

12. Which of the following law is associated with the fact that anterior spinal nerve roots contain only motor fibres and posterior roots only sensory fibres ?
(A) Magendie’s law 
(B) Bell’s law
(C) Both (A) and (B) 
(D) None of these
Ans : (C)

13. In birds—
(A) Left oviduct and right aortic arch are present
(B) Left oviduct and left aortic arch are present
(C) Right oviduct, left ovary and right aortic arch are present
(D) Left oviduct, left ovary and right aortic arch are present
Ans : (B)

14. Ancestral amphibians were tetrapods that evolved during—
(A) Devonian period
(B) Carboniferous period
(C) Jurassic period
(D) Cretaceous period
Ans : (B)

15. Community health services involves—
(A) Control of communicable diseases
(B) School and health education
(C) Awareness of clean environment
(D) All the above
Ans : (D)

16. The active rolling over of endodermal and mesodermal cells from the embryo surface into the interior is defined as—
(A) Ingression 
(B) Involution
(C) Epiboly 
(D) Inversion
Ans : (B)

17. The wall of heart is made up of—
(A) Epicardium 
(B) Myocardium
(C) Endocardium 
(D) All the above
Ans : (D)

18. Genetic counsellors can identify heterozygous individuals by—
(A) Height of individual
(B) Colour of individual
(C) Screening procedures
(D) All the above
Ans : (C)

19. Which of the following enzyme is secreted by intestinal mucosa that remain closely associated with the microvilli ?
(A) Peptidase 
(B) Disaccharidase
(C) Trypsin 
(D) Both (A) and (B)
Ans : (D)

20. Which of the following is absorbed by intestinal mucosa by active transport ?
(A) Galactose 
(B) Glucose
(C) Fructose 
(D) Both (A) and (B)
Ans : (D)

Zoology : Solved Paper

Zoology : Solved Paper

1. Bruch’s membrane is found in—
(A) Inner ear (B) Uvea of eye
(C) Testes (D) Pancreas

2. Which part of brain allows one side of brain to control opposite side of body ?
(A) Midbrain (B) Medulla
(C) Cerebellum (D) Pons

3. Fetuin is found in—
(A) Foetus (B) Liver
(C) Spleen (D) None of these

4. Hensen’s body is associated with—
(A) Retina of eye (B) Organ of Corti
(C) Heart (D) Skin

5. Sensory receptor of warmth located principally at the lip of fingers is known as—
(A) Ruffini’s corpuscles (B) Organ of Zuckerkandl
(C) Organ of Giraldes (D) Weber’s organ

6. Which of the following is basic amino acid ?
(A) Alanine (B) Aspartic acid
(C) Asparagine (D) Arginine

7. Which of the following amino acid is sulphurbearing compound ?
(A) Methionine (B) Alanine
(C) Aspartic acid (D) Arginine

8. Negri bodies are associated with—
(A) Rabies (B) Typhoid
(C) Tuberclosis (D) Hepatitis

9. Schultze’s bundle is associated with—
(A) Brain (B) Spinal cord
(C) Heart (D) None of these

10. Schlemm’s canal is present in—
(A) Eye (B) Cochlea
(C) Spinal cord (D) Vertebrae

11. Capsule of Tenon is associated with—
(A) Eyeball (B) Brain
(C) Skin (D) Kidney

12. Which of the following law is associated with the fact that anterior spinal nerve roots contain only motor fibres and posterior roots only sensory fibres ?
(A) Magendie’s law (B) Bell’s law
(C) Both (A) and (B) (D) None of these

13. In birds—
(A) Left oviduct and right aortic arch are present
(B) Left oviduct and left aortic arch are present
(C) Right oviduct, left ovary and right aortic arch are present
(D) Left oviduct, left ovary and right aortic arch are present

14. Ancestral amphibians were tetrapods that evolved during—
(A) Devonian period (B) Carboniferous period
(C) Jurassic period (D) Cretaceous period

15. Community health services involves—
(A) Control of communicable diseases (B) School and health education
(C) Awareness of clean environment (D) All the above

16. The active rolling over of endodermal and mesodermal cells from the embryo surface 
into the interior is defined as—
(A) Ingression (B) Involution
(C) Epiboly (D) Inversion

17. The wall of heart is made up of—
(A) Epicardium (B) Myocardium
(C) Endocardium (D) All the above

18. Genetic counsellors can identify heterozygous individuals by—
(A) Height of individual (B) Colour of individual
(C) Screening procedures (D) All the above

19. Which of the following enzyme is secreted by intestinal mucosa that remain closely associated with the microvilli ?
(A) Peptidase (B) Disaccharidase
(C) Trypsin (D) Both (A) and (B)

20. Which of the following is absorbed by intestinal mucosa by active transport ?
(A) Galactose (B) Glucose
(C) Fructose (D) Both (A) and (B)

21. A starving person consumes first—
(A) Body fats (B) Body proteins
(C) Vitamins (D) Stored glycogen

22. The functional unit of contractile system in striated muscle is—
(A) Cross bridges (B) Sarcomeres
(C) Myofibril (D) Z-band

23. Globular proteins undergo structural changes in response to extremes of pH or temperature, is called—
(A) Renaturation (B) Denaturation
(C) Combination (D) Both (A) and (B)

24. The study of relationships between size and shape is known as—
(A) Allometry (B) Heterochrony
(C) Isometry (D) Allochrony

25. A localised tumour covered by connective tissue is called—
(A) Metastasis (B) Neoplasm
(C) Benign tumour (D) Malignant tumour

26. Hürthle cell is associated with—
(A) Thyroid gland (B) Pituitary gland
(C) Adrenal gland (D) Pancreas

27. A metastatic cancerous tumour is termed ‘sarcoma’, if the disorder is in—
(A) Immune system (B) Epithelial cells
(C) Fibroblasts (D) Circulatory system

28. Graft between isogenic individuals is known as—
(A) Syngraft (B) Allograft
(C) Xenograft (D) None of these

29. The most striking example of point mutation is found in a disorder called—
(A) Thalassemia (B) Nightblindness
(C) Down’s syndrome (D) Sickle-cell anaemia

30. The phenomenon of ‘industrial melanism’ demonstrates—
(A) Natural selection (B) Induced mutation
(C) Reproductive isolation (D) Geographical isolation

31. Overproduction of which of the following neurotransmitter has been associated with the mental disorder ‘Schizophrenia’ ?
(A) Acetylcholine (B) GABA
(C) Dopamine (D) Serotonin

32. Milk tastes sour when kept in the open for sometime due to for-mation of—
(A) Carbonic acid (B) Lactic acid
(C) Citric acid (D) Malic acid

33. Red tide is caused by—
(A) Protozoans (B) Corals
(C) Dinoflagellates (D) All the above

34. A type of hypersensitivity to allergen in which humoral antibodies attach to mast cells and basophils, may result in circulatory shock, is called—
(A) Orthopnea (B) Anaphylaxis
(C) Rhinitis (D) Immunologic surveillance

35. Organisms with very high intrinsic growth rates have—
(A) Long generation times (B) Short generation times
(C) No courtship behaviours (D) No carrying capacity

36. Which of the following organism is iteroparous ?
(A) Pacific salmon fish (B) Virus
(C) Bacteria (D) Humans

37. A micromutation is—
(A) Polyploidy (B) Addition of chromosome
(C) Deletion of chromosome (D) Change in gene frequency

38. The limited period of sexual receptivity that occurs around the time of ovulation in all
female mammals except humans is called—
(A) Menstruation (B) Luteinization
(C) Oogenesis (D) Estrus

39. The rate and force of the heart-beat, and the secretion of digestive glands are controlled by—
(A) Central nervous system (B) Spinal nerves
(C) Cranial nerves (D) Autonomic nervous system

40. Glycosidic bond is broken during digestion of—
(A) Protein (B) Starch
(C) Lipid (D) All the above

41. Postganglionic parasympathetic fibres are—
(A) Adrenergic (B) Cholinergic
(C) Both (A) and (B) (D) None of these

42. In glycosuria disorder, urine contains—
(A) Amino acid (B) Inorganic ions
(C) Glucose (D) Epithelial cells

43. Mammillary bodies are attached to the ventral side of—
(A) Olfactory lobe (B) Cerebral hemisphere
(C) Diencephalon (D) Medulla oblongata

44. Argentaffin cells are associated with—
(A) Tumour (B) Heart muscle
(C) Pericardium (D) Pelvis of kidney

45. Sweating on palm and sole due to psychic stimuli is called—
(A) Bradykinin (B) Blushing
(C) Cold sweat (D) None of these

46. Inherited Rh gene is found in—
(A) Rh⁺ individuals (B) Rh^– individuals
(C) AB blood group individuals (D) O blood group individuals

47. The ‘soft spot’ on the top of an infant’s skull is called—
(A) Suture (B) Fontanel
(C) Ligament (D) Fascia

48. Concentration of carbonic acid does not increase in blood due to the presence of—
(A) Na⁺ (B) K⁺
(C) Ca⁺⁺ (D) Mg⁺⁺

49. Staph food poisoning is related with—
(A) Salmonella bacteria (B) Clostridium bacteria
(C) Staphylococcus bacteria (D) None of these

50. Capacitation is—
(A) Final stage in maturation of spermatozoa (B) Final stage in fertilization
(C) Maturation of ovum (D) All of these

Answers with Hints
1. (B) Bruch’s membrane is a glassy membrane of the uvea of eye lying between the choroids membrane and the pigmented epithelium of the retina. It is also known as lamina basalis of the choroid or vitreous lamella.
2. (B) Medulla contains ascending sensory and descending motor nerves, and contains site where major motor nerves cross to opposite side of nervous system, allowing one side of brain to control opposite side of body.
3. (A) Fetuin is a type of globulin found in foetus and is required for the cell proliferation
and growth of foetus. 
4. (B) Hensen’s body is modified Golgi net found in the hair cells of the Organ of Corti.
5. (A) Ruffini’s corpuscles are encapsulated sensory nerve endings found in subcutaneous
tissue of finger tips and thought to mediate sense of warmth.
6. (D) Arginine is crystalline basic amino acid obtained from decomposition of vegetable
tissues, protamines and proteins. 
7. (A)
8. (A) Negri bodies are very minute bodies formed in nerve cells of the brain of one affected by rabies.
9. (B) Schultze’s bundle is commashaped path of fibres in middle of spinal cord’s fasciculus cuneatus.
10. (A) Schlemm’s canal is space or series of spaces at the junction of the sclera and the cornea of the eye into which aqueous humor is drained from the anterior chamber through
the pectinate villi.
11. (A) Capsule of Tenon is a thin fibrous sac enveloping the eyeball, forming a socket in
which it rotates.
12. (C) 13. (B)
14. (B) Carboniferous was the recent period of the Palaeozoic, some 355–280 million years ago. It was characterized by the evolution amphibians on swampy land, a few primitive early reptiles and giant ferns.
15. (D)
16. (B) Involution is rolling over of cells during gastrulation from the surface towards interior of the developing gastrula.
17. (D) Heart’s wall possesses three layers, i.e., the outer epicardium (serous layer), the middle myocardium (cardiac muscle), and the inner endocardium. Endocardium lines the four chambers of the heart and covers the valves. 
18. (C) Carriers of genetic disorders (those heterozygous for the condition, but who do not themselves exhibit it) can be diagnosed through screening procedures during genetic
counselling.
19. (D) The epithelial cells of the intestinal mucose manufacture and secrete peptidase and disaccharidase digestive enzymes. They are not released into the lumen of the intestine but remain closely associated with the microvilli of the epithelial cells.
20. (D) The glucose and galactose enter intestinal mucosa by active transport, while fructose enters by facilitated diffusion.
21. (D) The liver stores glycogen to fulfil body’s requirement of glucose for energy during starvation.
22. (B)
23. (B) Changes occurring to molecules of globular proteins and nucleic acid in solution in response to extremes of pH or temperature is called denaturation.
24. (A) Allometry is the study of relationship between size and shape. Organisms do not grow isometrically, rather proportions change as size changes.
25. (C)
26. (A) Hürthle cell is benign or malignant tumour of the thyroid gland. The cells are large and acidophilic.
27. (C) Sarcomas are cancer of connective tissues. Fibroblast is the characteristic cell type of vertebrate connective tissue.
28. (A) Syngraft is also known as isograft. It is a kind of grafting between isogenic individuals such as identical twins.
29. (D) Point mutations involve minor changes in the genetic material, often single base-pair substitution. Sickle-cell anaemia is genetically determined disorder, caused by homozygosity, producing a single amino acid substitution in the b-chain of the normal haemoglobin molecule. 
30. (A) Industrial melanism provides one of the best examples of evolution within species and of natural selection.
31. (C) Dopamine is a neurotransmitter whose low concentration produces symptoms of Parkinson’s disease and over production causes Schizophrenia.
32. (B) Lactic acid is a carboxylic acid, formed in metabolism of many bacteria. In milk, lactose is converted into lactic acid by metabolic activities of bacteria. Lactic acid
gives sour taste to milk. 
33. (C) Red tide is reddish discolouration of coastal surface waters due to concentrations of certain toxin producing dinoflagellates.
34. (B) Anaphylaxis is a type of hypersensitivity resulting due to interaction of humoral antibodies with mast cells and basophils.
35. (B) 36. (D)
37. (D) Mutations which are large and conspicuous are called macromutations and those very inconspicuous are called micromutation. Change in the genic frequency is the constituent of microevolution.
38. (D) Estrus is the cyclic period of sexual activity in non human female mammals, characterized by congestion of and secretion by the uterine mucosa. During estrus the animal is said to be ‘in heat’.
39. (D) 40. (B)
41. (B) Cholinergic fibres include all preganglionic fibres, all postganglionic parasympathetic fibres, which liberate acetylcholine at their nerve endings.
42. (C)
43. (C) A pair of small rounded bodies, the mammillary bodies lie behind the infundi-bulum in Diencephalon.
44. (A) Argentaffinoma is tumour, having argentaffin cells.
45. (C) 46. (A)
47. (B) In a newborn infant, the bones of the skull are still developing and these are relatively wide spaces between them. The spaces contain tough sheets of connective tissue that connect the bones and are called fontanels.
48. (A)
49. (C) Staph food poisoning, once known as ptomaine poisoning, results from toxins produced by Staphylococcus bacteria growing on food.
50. (A) Capacitation is the final stage in maturation of mammalian spermatozoa, without
which they cannot engage in fertilization.