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CBSE

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The natural phenomena responsible for deforestation in the forest is _________.

  1. overgrazing by cattles

  2. cutting of trees

  3. fires in the forest

  4. slash and burn method


Correct Option: C
Explanation:

Yes, it is correct. The temperature at which a substance ignites and begins to burn is called the flash point. The flash point of wood is 572 degrees. Once wood reaches its flash point, it creates a substance which reacts with oxygen to create a flame. The flame heats the wood, which then spreads the flame. This process explains how fires can spread even in very cold weather. Lightning and earth quakes are the main reasons for this.

What is red data book?

  1. It maintains a record of the protected flora and fauna areas.

  2. It gives information about threatened habitats and species.

  3. It gives information about the behaviour of various species.

  4. It gives the information on endangered species.


Correct Option: A
Explanation:

 Yes, it is correct. It maintains the record of all flora and fauna species that are endangered.

Which of the following structures is found in large number in a plant cell ?

  1. Nucleus

  2. Vacuole

  3. Cytoplasm

  4. Chloroplast


Correct Option: D
Explanation:

 Yes, it is correct. Plant cell has many chloroplasts. Chloroplasts are distributed in a plant cell. They trap sunlight to aid in photosynthesis.

Which of the following pairs belongs to the same type?

  1. Euglena and paramecium

  2. Bacteria and fungi

  3. Blue green algae and euglena

  4. Paramecium and bacteria


Correct Option: A
Explanation:

 Yes, this is correct as this is the only pair in which both are eukaryotes. Their cells have a well organized nucleus.

When we refer to eye colour which of the following options are we actually talking about?

  1. Iris

  2. Cornea

  3. Lens

  4. Retina


Correct Option: A
Explanation:

Yes, it is correct. Eye colour is the colour of iris. It can be blue, gray, green, black or brown.

Which organisms young ones resemble their adult?

  1. Butterfly

  2. Frog

  3. Silkworm

  4. Human


Correct Option: D
Explanation:

 Yes, it is correct. There are some organisms in which the young ones resemble their adults and humans are one of them.

Which statement is incorrect?

  1. The cell membrane is the outer most covering of the cell.

  2. The cell membrane is also known as plasma membrane.

  3. The cell wall is present in algae, fungi, bacteria and plants.

  4. The cell wall is absent in animal cells and protozoa.


Correct Option: A
Explanation:

 Yes, it is the incorrect statement. Cell wall is the outermost covering of the cell. If it is not present then cell membrane is the outermost covering.

What is the shape of white blood cells?

  1. Round

  2. Long and branched

  3. Elongated spindle shaped

  4. No particular shape


Correct Option: D
Explanation:

 Yes, it is correct. White blood cells do not have any particular shape. Its like amoeba, no definite shape.

Which microorganisms require cells of host to reproduce?

  1. Bacteria

  2. Protozoa

  3. Virus

  4. Algae


Correct Option: C
Explanation:

 Yes, it is correct. Virus require cells of host to reproduce.The process is called lytic cycle.

Place a moist bread near your window, you will observe small black round structures growing on it. What is that?

  1. The dust gets accumulated in the pores.

  2. Microorganisms

  3. The colour of flour changes due to exposure to atmosphere.

  4. None of these


Correct Option: B
Explanation:

 Yes, it is correct. As microorganisms are present everywhere (in water, air, and soil). In fact, micro-organisms can survive under all types of environment. The black round structure seen growing when observed under microscope was found to be microorganisms.

Which of the following diseases is not carried by a housefly?

  1. Malaria

  2. Cholera

  3. Typhoid

  4. Dysentery


Correct Option: A
Explanation:

 Yes, it is correct as malarial parasite is transmitted from one place to another by female Anopheles mosquito and not by a housefly.

Which statement is not correct?

  1. Yeast is used in preparation of bread, pastries and cakes.

  2. Yeast is used in curdling of milk.

  3. Yeast is used in commercial production of alcohol and vine.

  4. Yeast acts on sugar and converts it into alcohol.


Correct Option: B
Explanation:

Yes, it is the correct answer. This is the only incorrect statement. Lacto bacillus (bacteria) promotes the conversion of milk into curd, not yeast.

Tetracycline, penicillin, streptomycin and erythromycin are the names of ________.

  1. Diseases

  2. Bacteria

  3. Antibiotics

  4. Vaccinations


Correct Option: C
Explanation:

Yes, it is correct. These are the names of commonly used antibiotics obtained from different bacteria and fungi.

Which pair of fabric is made up from animals?

  1. Jute and silk

  2. Cotton and jute

  3. Silk and wool

  4. Wool and cotton


Correct Option: C
Explanation:

Yes, it is correct. Both are obtained from animals. Silk is obtained from silk worm and wool from sheep or rabbit, etc.

Which of the following organisms can reproduce both sexually and asexually?

  1. Plasmodium

  2. Hydra

  3. Fungi

  4. Humans


Correct Option: A
Explanation:

 Yes, it is correct. In plasmodium, asexual or sexual reproduction takes place. It depends on their life cycle.

Where is Pituitary gland situated?

  1. Throat

  2. Above the kidneys

  3. Brain

  4. Back side of neck


Correct Option: C
Explanation:

 Yes, it is the correct answer. It releases the harmones that control the activity of other endocrine glands. It also releases growth harmones.

Manures do not __________.

  1. improve soil texture

  2. improve water retaining capacity of soil

  3. replenish nutrients in the soil

  4. make soil less fertile in long run


Correct Option: D
Explanation:

 Yes, it is correct. Manures which are decomposed organic matter increase the nutrient content of soil for healthy growth of plants. They are the fertilizers which in long run make the soil less fertile.

Which one is not a water borne disease?

  1. Tuberculosis

  2. Typhoid

  3. Hepatitis B

  4. Cholera


Correct Option: A
Explanation:

Yes, it is correct. It is an air borne diseses. Patient should be kept in isolation.

When does Menarche occur in a female?

  1. During puberty

  2. During menopause

  3. During labour pain

  4. After menopause


Correct Option: A
Explanation:

 Yes, it is correct. In the female, the production and release of ova or the egg follows a cyclic process every 28-30 days. This cycle is governed by hormones and is called the menstrual cycle. The first menstruation is called menarche. Menarche occurs during puberty.

A plant cell ________.

    1. has a cell wall 2. has chloroplast 3. has many vacuoles 4. has a centrally placed nucleus
    1. has a cell wall 2.has chloroplast 3. has a centrally placed vacuole 4. has a nucleus which is present near the side wall of a cell
    1. has a cell wall 2. has chloroplast 3. has a centrally placed vacuole 4. has a nucleus which is present near the side wall of cell
    1. has a cell wall 2. does not have chloroplast 3. has a centrally placed vacuole 4. has a centrally placed nucleus

Correct Option: C
Explanation:

 Yes, it is correct as a plant has a cell wall, chloroplast, a centrally placed vacoule and a nucleus, present near the side wall.

What is pasteurization?

  1. It is a method of preserving milk which involves hot treatment only.

  2. It is a method of preserving milk which involves cold treatment only.

  3. It is a method of preserving milk, which involves both hot and cold treatments.

  4. It is a method of preserving milk which involves preservatives from outside to be added.


Correct Option: C
Explanation:

 Yes, it is correct as pasteurization involves the boiling of milk at temperature 700C and then rapid cooling to store it.

Which human cells have no nucleus?

  1. Muscle cells

  2. Red blood cells

  3. White blood cells

  4. Nerve cell


Correct Option: B
Explanation:

 Yes, it is correct. The red blood cells in humans contain no nucleus.

What are chromoplasts?

  1. These are plastids which are red, yellow or orange in colour.

  2. These are colourless plastids

  3. These are green coloured plastids.

  4. None of these


Correct Option: A
Explanation:

 Yes, it is correct. This is a type of plastid which have yellow, orange or red colour. It is found in petals of flower, fruits, etc. This colour is due to two pigments, carotene and xanthophyll.

What cannot be added to the food items to prevent them from getting spoilt?

  1. Salt

  2. Sugar

  3. Oil

  4. Water


Correct Option: D
Explanation:

Yes, it is correct. Water is not used as preservative for food item as it favours the growth of microorganisms which spoil the food.

Which statement doesn't describe chloroplast?

  1. It is disc shaped.

  2. Chloroplast is the site for photosynthesis.

  3. It has watery fluid rich in protein known as stroma.

  4. It occurs in those parts of plants which are not exposed to light.


Correct Option: D
Explanation:

 This is the correct answer as it does not describe the chloroplast. Instead it is the leucoplast present in those parts which are not exposed to sunlight.

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