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SSC > Biology

Explore popular questions from Biology for SSC. This collection covers Biology previous year SSC questions hand picked by experienced teachers.

Q 1.

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Which wood will become useless soon after exposing in the open air?

A

Softwood

B

Fibrous wood

Wet wood

D

Hard wood

Explanation

Wood is a porous material and will absorb moisture from the air. Moisture is attracted to the walls of the tubes that make up the wood. Wood will only decay if it is in contact with the ground or wetted by an external source of moisture, such as rain seepage, plumbing leaks, or condensation. Dry wood will never decay. Also, the drier the wood, the less likely it is to be attacked by most types of wood-inhabiting insects. Wood-inhabiting fungi are small plants that lack chlorophyll and use wood as their food source. All fungi require moisture, oxygen, warmth, and food. The keys to preventing or controlling growth of fungi in wood in buildings are to either keep the wood dry (below moisture content of 20 percent) or to use preservative-treated or naturally resistant heartwood or selected species.

Q 2.

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Fruits of this plant are found underground :

A

Potato

B

Carrot

Groundnut

D

Onion

Explanation

The peanuts, or groundnut (Arachishypogaea), is a species in the legume "bean" family (Fabaceae). The cultivated peanut was probably first domesticated in the valleys of Peru. It is an annual herbaceous plant growing tall.

Q 3.

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Reserpine is used to :

reduce high blood pressure

B

increase blood pressure when it is low

C

alleviate pain

D

cure arthritis

Explanation

Reserpine (Lannett's Serpalan) is an indole alkaloid antipsychotic and antihypertensive drug that has been used for the control of high blood pressure. The antihypertensive actions of reserpine are a result of its ability to deplete catecholamines (among other monoamine neurotransmitters) from peripheral sympathetic nerve endings. These substances are normally involved in controlling heart rate, force of cardiac contraction and peripheral resistance.

Q 4.

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'ELISA' test is employed to diagnose :

A

Polio virus

B

AIDS antibodies

Tuberculosis bacterium

D

Cancer

Explanation

ELISA is an abbreviation for "enzyme-linked immuno-sorbent assay." An ELISA test uses components of the immune system and chemicals to detect immune responses in the body (for example, to infectious microbes).It is used to detect the retrovirus antibodies. The ELISA test involves an enzyme (a protein that catalyzes a biochemical reaction). It also involves an antibody or antigen (immunologic molecules).

Q 5.

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Why excessive heating and repeated use of cooking oil is most undesirable?

A

The oil vapours can cause indoor pollution

Carcinogenic substances like benzpyrene are produced

C

Nutrient value of food is lost

D

Loss and wastage of oil

Explanation

Heating an oil changes its characteristics and this means that oils regarded as being healthy at room temperature can become unhealthy when heated above certain temperatures. The smoking point is the temperature at which a particular fat or oil starts to smoke and break down creating acreolein, an obnoxious-smelling compound. A 2001 review found that polyunsaturated oils like soya, canola, sunflower, and corn oil degrade quickly to yield toxic compounds when heated and that prolonged consumption of these degraded polyunsaturated oils was linked to atherosclerosis, inflammatory joint disease and the development of birth defects.

Q 6.

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Which one of the following is a female sex hormone?

Estrogen

B

Androgen

C

Oxytocin

D

Insulin

Explanation

Estrogen is the general name for a group of hormone compounds. It is the main sex hormone in women and is essential to the menstrual cycle. Although both men and women have this hormone, it is found in higher amounts in women, especially those capable of reproducing. Secondary sex characteristics, which are the defining differences between men and women that don't relate to the reproductive system, are determined in part by estrogen.

Q 7.

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Clove, the commonly used spice, is obtained from the :

A

root

B

stem

flower bud

D

fruit

Explanation

Cloves are the aromatic dried flower buds of a tree in the family Myrtaceae. The clove tree is an evergreen that grows to a height ranging from 8-12 m, having large leaves and sanguine flowers in numerous groups of terminal clusters. The flower buds are at first of a pale colour and gradually become green, after which they develop into a bright red, when they are ready for collecting.

Q 8.

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Labourers who do hard manual labour develop thick skin on their palms and soles due to :

A

thick epidermis

B

thick dermis

C

thick subcutaneous tissue

All of these

Explanation

If we look at the dermis, the layer on the skin beneath the epidermis (outer layer), and a certain type of cell within this layer, called a fibroblast, we find that the fibroblasts in the soles and palms secrete higher levels of a protein known as dickkopf 1, or DKK1, than the fibroblasts in the dermis at other body sites. It is believed that the rich source of DKK1 in these areas affects the epidermal layer above it and creates the physical characteristics of thickened, paler skin. DKK1 thickens the epidermis by increasing the number of skin cells and their density. Three genes affected by DKK1 - keratin 9, aKLEIP and a-catenin - have been found to cause this thickening. Keratin 9 reinforces the skin against physical impact, aKLEIP aids in cell division (multiplying) and makes cells smaller and, finally, a reduction in a-catenin is also possibly involved in cell contraction (making the cells more compact).

Q 9.

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Maximum photosynthetic activity occurs in :

blue and red region of light

B

green and yellow region of light

C

blue and orange region of light

D

violet and orange region of light

Explanation

Wavelength of light between 400 nm and 700 nm is most effective for photosynthesis. This light is called photosynthetically active radiation (PAR). Comparatively more photosynthesis occurs is red and blue regions though others have significant net photosynthesis. light has maximum efficiency in red and minimum in blue region. In both these regions light is absorbed by chlorophylls. Red light favours more carbohydrate accumulation while blue light more protein synthesis.

Q 10.

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AIDS virus has :

single-stranded RNA

B

double-stranded RNA

C

single-stranded DNA

D

double-stranded DNA

Explanation

AIDS viruses have single stranded RNA. It is composed of two copies of positive single-stranded RNA that codes for the virus's nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein. The single-stranded RNA is tightly bound to nucleocapsid proteins.

Q 11.

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A 'breath test' used by traffic police to check drunken driving uses:

potassium dichromate-sulphuric acid

B

potassium permanganate-sulphuric acid

C

turmeric on filter paper

D

silica gel coated with silver nitrate

Explanation

The main constituent of alcohol is Ethanol and the concentration of ethanol in a sample can be determined by back titration with acidified potassium dichromate. Reacting the sample with an excess of potassium dichromate, all ethanol is oxidized to acetic acid. One major application for this reaction is in old police breathanalyzer tests. When alcohol vapor makes contact with the yellow dichromate-coated crystals, the color changes from yellow to green. The degree of the color change is directly related to the level of alcohol in the suspect's breath.

Q 12.

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Anglo-Nubian is a breed of:

A

sheep

goat

C

poultry

D

cattle

Explanation

The Anglo-Nubian, or simply Nubian in the United States, is a breed of domestic goat. The breed was developed in Great Britain of native milking stock and goats from the Middle East and North Africa. Its distinguishing characteristics include large, pendulous ears and a "Roman" nose. Due to their Middle-Eastern heritage, Anglo-Nubians can live in very hot climates and have a longer breeding season than other dairy goats. Considered a dairy or dual-purpose breed, Anglo-Nubians are known for the high butterfat content of their milk, although on average, the breed produces less milk than other dairy breeds.

Q 13.

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What kind of soil is treated with gypsum to make it suitable for cropping?

Alkaline

B

Acidic

C

Water-logged

D

Soil with excessive clay content

Explanation

Alkaline soils are treated with gypsum to make it suitable for cropping. Alkaline soils are clay soils with high pH (> 9), a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate which causes the soil to swell and difficult to settle. Gypsum (calcium sulphate, CaS0{tex}_4{/tex}. 2H{tex}_2{/tex}0) can also be applied as a source of Ca++ ions to replace the sodium at the exchange complex. There must be enough natural drainage to the underground, or else an artificial subsurface drainage system must be present, to permit leaching of the excess sodium by percolation of rain and/or irrigation water through the soil profile.

Q 14.

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Typhoid fever is caused by-

A

virus

bacteria

C

fungus

D

allergy

Explanation

Typhoid fever, also known as typhoid, is a common worldwide bacterial disease, transmitted by the ingestion of food or water contaminated with the feces of an infected person, which contain the bacterium Salmonella typhi, serotype Typhi.

Q 15.

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Which of the following blood group is a universal recipient?

A

A

B

B

AB

D

O

Explanation

Blood group AB individuals have both A and B antigens on the surface of their RBCs, and their blood plasma does not contain any antibodies against either A or B antigen. Therefore, an individual with type AB blood can receive blood from any group (with AB being preferable), but cannot donate blood to either A or B group. They are known as universal recipients.

Q 16.

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Rod shaped bacteria is called

Bacillus

B

Spirillum

C

Coccus

D

Coma

Explanation

Bacillus is a genus of Gram-positive, rod-shaped bacteria and a member of the phylum Firmicutes. Bacillus species can be obligate aerobes or facultative anaerobes, and test positive for the enzyme catalase. Bacillus includes both free-living and pathogenic species. Under stressful environmental conditions, the cells produce oval endospores that can stay dormant for extended periods.

Q 17.

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The animal which has become extinct recently in India happens to be

A

Golden cat

Cheetah

C

Wooly wolf

D

Rhinoceros

Explanation

Cheetahs have been known to exist in India for a very long time, but as a result of hunting and other causes, cheetahs have been extinct in India since the 1940s.The cheetah is the only animal that has been described extinct in India in the last 100 years.

Q 18.

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Which one of the following is not a true fish ?

Silver fish

B

Saw fish

C

Hammer fish

D

Sucker fish

Explanation

Lepisma saccharina, frequently called a silverfish or fishmoth is a small, wingless insect in the order Thysanura. Silverfish are always wingless and are silvery to brown in colour because their bodies are covered with fine scales. They are generally soft bodied. Its common name derives from the animal's silvery light grey and blue colour, combined with the fish-like appearance of its movements, while the scientific name indicates the silverfish's diet of carbohydrates such as sugar or starches.

Q 19.

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By which the sex of a child is determined before birth ?

A

Sperms of father

Foetus of mother

C

Both (1) and (2)

D

Nutrition of mother

Explanation

The gender of the baby can be ascertained accurately after more or less than seven weeks of pregnancy. During this period of pregnancy, the fetal DNA is sufficiently found in the mother's blood. Thus, identifying the fetus gender through prenatal gender testing is easier.

Q 20.

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How many feet has a crab got?

A

12

B

10

8

D

6

Explanation

Crabs are crustaceans with eight walking legs and two legs that are sometimes used for walking but usually used for eating. These are its pincers and they are called chela. The front two legs are called chelipeds.

Q 21.

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Edward Jenner is associated with

A

Cholera

B

Typhoid

Small Pox

D

Paralysis

Explanation

Edward Anthony Jenner, (17 May, 1749 - 26 January, 1823) was an English physician and scientist from Berkeley, Gloucestershire, who was the pioneer of smallpox vaccine. He is often called "the father of immunology", and his work is said to have "saved more lives than the work of any other man". Jenner contributed papers on angina pectoris, ophthalmia, and cardiac valvular disease and commented on cowpox.

Q 22.

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Which among the following living being has respiratory organ but does not have brain ?

A

crab

starfish

C

blood succor

D

silverfish

Explanation

Starfish do not have many well-defined sensory inputs, they are sensitive to touch, light, temperature, orientation, and the status of water around them. The tube feet, spines, and pedicellariae found on starfish are sensitive to touch, while eyespots on the ends of the rays are light-sensitive. The tube feet, especially those at the tips of the rays, are also sensitive to chemicals and this sensitivity is used in locating odour sources such as food.

Q 23.

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Which one of the following elements is associated with teeth disorder ?

A

Chlorine

Fluorine

C

Bromine

D

Iodine

Explanation

Fluorine is the element that is associated with teeth disorder because the presence of sodium fluoride in drinking water at the level of 2 ppm may cause mottled enamel in teeth, skeletal fluorosis, and may be associated with cancer and other diseases. However, topically applied fluoride (toothpaste, dental rinses) has been shown to help reduce dental caries.

Q 24.

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What is the number of chromosomes in a normal human body cell?

A

43

B

44

C

45

46

Explanation

A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. Human cells have 23 pairs of chromosomes (22 pairs of autosomes and one pair of sex chromosomes), giving a total of 46 per cell.

Q 25.

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Excretory products of mammalian embryo are eliminated out by

Placenta

B

Amniotic fluid

C

Allantois

D

Ureter

Explanation

The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and lizards with varying levels of development up to mammalian levels.