Test: Class 8 General Science NCERT Based - 3


30 Questions MCQ Test NCERT based Tests for UPSC CSE | Test: Class 8 General Science NCERT Based - 3


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QUESTION: 1

Which of the following statements is not correct about deforestation?

Solution:
  • Deforestation means that less carbon dioxide will be taken up by the plants, resulting in an increase in its amount in the atmosphere.

  • This will lead to global warming as carbon dioxide traps the heat rays reflected by the earth. Deforestation also lowers the ground water level. The major reason behind the changes of soil properties is deforestation. This causes soil erosion. Soil erosion lowers the content of humus in soil and soil fertility also declines. Soil erosion also causes desertification.

  • Deforestation adversely affects the water holding capacity of the soil. The movement of water from the soil surface into the ground (infiltration rate) is reduced. This is responsible for floods.

QUESTION: 2

Consider the following statements:

1. The plants and animals found in a particular area are termed flora and fauna of that area.

2. Endemic species are those species of plants and animals which are found exclusively in a particular area.

Which of the statements given above is/are correct?

Solution: The plants and animals found in a particular area are termed as flora and fauna of that area. Endemic species are those species of plants and animals which are found exclusively in a particular area. They are not naturally found anywhere else.

QUESTION: 3

To protect the flora, fauna and their habitat; certain protected areas have been marked. Which of the following protected areas is/are correctly matched?

1. Sanctuaries: Places where killing (poaching) or capturing of animals is strictly prohibited.

National Parks: Protected areas for the wildlife, where they can live freely and utilise the natural resources.

2. Biosphere Reserves: The biosphere reserves help to maintain the variety of plants, animals and microorganisms along with the culture generally found in an area.

Which of the statements given above is/are correct?

Solution:
  • Of the various places meant for the protection of the flora and fauna, sanctuaries, national parks and biosphere reserves are the primary.

  • Wildlife sanctuaries provide protection and suitable living conditions to wild animals. Sanctuaries are places where killing (poaching) or capturing of animals is strictly prohibited. Hence, the wildlife and their habitat are protected from any form of interference.

  • The local population and certain human interference is allowed, which makes it different from biosphere reserves. National Parks are protected spaces for the wildlife, where any form of human interference is prohibited.

QUESTION: 4

Consider the following statements about Pachmarhi Biosphere Reserve:

1. The Pachmarhi Biosphere Reserve consists of one national park named Pench and two wildlife sanctuaries called Bori and Pachmarhi.

2. Bison, Indian giant squirrel and Flying squirrel are the Endemic Fauna of Pachmarhi Biosphere reserve.

3. Rock shelters are also found inside the Satpura National Park. These are the prehistoric evidences of human life in these jungles. They give us an idea of the life of the primitive people. Rock paintings are found in these shelters.

Which of the statements given above is/are correct?

Solution:
  • Statement 1 is not correct because the Pachmarhi Biosphere Reserve consists of one national park named Satpura and two wildlife sanctuaries named Bori and Pachmarhi. Satpura National Park is India’s first Reserve forest.

  • The best form of teak is found in this region. Bison, Indian giant squirrel and Flying squirrel are the Endemic Fauna of Pachmarhi Biosphere reserve; and Sal and wild mango are the Endemic Flora.

  • Sal, teak, mango, jamun, silver ferns, arjun, etc are the flora and chinkara, blue-bull, barking deer, cheetah, leopard, wild dog, wolf, etc. are examples of the fauna of the Pachmarhi Biosphere Reserve. Rock shelters are also found inside the Satpura National Park. Rock paintings are found in these shelters.

QUESTION: 5

Which of the following statements is/are correct regarding the Red Data Book?

1. It is a book which records all the Endemic Species of a region.

2. It is a book where the records of Biosphere Reserves are maintained.

3. It is a book which maintains the records of all the endangered species.

Select the correct option from the codes given below:

Solution:
  • Red Data book is a book which maintains a record of all the endangered species. There are separate Red Data Books for plants, animals and other organisms.The endangered species are protected in Wildlife sanctuaries.

  • Large and small, all types of animals are protected in these sanctuaries, because their contribution to the ecosystem cannot be ignored. Small organisms face the danger of extinction much more than larger animals.

QUESTION: 6

Which of the following is/are part of the ecosystem?

Solution: For any given area, all the plants, trees, organisms, microorganisms, non living things, like water, soil, river, delta, sunlight, etc together comprise the ecosystem.

QUESTION: 7

Which of the following statements is related to the Ex situ conservation?

Solution:
  • Ex-situ conservation involves maintenance and breeding of endangered plants and animals under partially or wholly controlled conditions in specific areas including zoos, gardens, nurseries, etc. That is, the conservation of selected plants and animals in selected areas outside their natural habitat is known as ex-situ conservation.

QUESTION: 8

On which date International Day for Biodiversity is observed?

Solution:
  • The United Nations has proclaimed May 22 The International Day for Biological Diversity (IDB) to increase understanding and awareness of biodiversity issues. When first created by the Second Committee of the UN General Assembly in late 1993, 29 December (the date of entry into force of the Convention of Biological Diversity), was designated The International Day for Biological Diversity.

  • In December 2000, the UN General Assembly adopted 22 May as IDB, to commemorate the adoption of the text of the Convention on 22 May 1992 by the Nairobi Final Act of the Conference for the Adoption of the Agreed Text of the Convention on Biological Diversity.

  • This was partly done because it was difficult for many countries to plan and carry out suitable celebrations for the date of 29 December, given the number of holidays that coincide around that time of year.

QUESTION: 9

Find out the correct definition of 'Biodiversity'.

Solution: The term biodiversity (from “biological diversity”) refers to the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life. Biodiversity is important to most aspects of our lives.

QUESTION: 10

What does the term 'MIKE' stand for?

Solution: The Monitoring the Illegal Killing of Elephants (MIKE) programme is an international collaboration that measures the levels, trends and causes of elephant mortality, thereby providing an information base to support international decision-making related to conservation of elephants in Asia and Africa.

QUESTION: 11

Consider the following statements regarding in vitro fertilization.

1. In this technique, after fertilization, the zygote is allowed to develop for 7 days and then transferred to the mother’s uterus.

2. Baby born through this method is called a test tube baby; because the development of the baby occurs in a test tube.

Which of the statements given above is/are correct?

Solution:
  • Fertilization occurring outside the body, artificially, is called in vitro fertilization. If the sperms are unable to reach the egg, due to blockage in the oviduct, the doctor collects fresh sperms and eggs; and fertilizes them in appropriate media for several hours, to bring about IVF or In vitro fertilization.

  • If fertilization occurs, the zygote is allowed to develop for around a week, following which, it is transferred to the mother’s uterus.

  • The test tube baby is born like any other baby and its complete development takes place in the uterus. A baby born through this technique is called a test tube baby. This is misleading because babies do not grow in a test tube.

QUESTION: 12

The first step of reproduction is called fertilization. Consider the following statements regarding reproduction of organisms.

1. The fusion of sperms and ovum is called fertilization.

2. Fertilization in all oviparous animals occurs outside the female body.

Which of the above given statements/statements is/are correct?

Solution:
  • Sperm and ovum, both are examples of single celled bodies. The fusion of both is called fertilization, the result of which is the formation of zygote. The cells of zygote divide continuously, to form a ball of cells, after which, the cells differentiate and divide into tissues and organs. This is called an embryo.

  • The embryo undergoes development after being implanted on the wall of the uterus. The stage of embryo development, wherein all the body parts are distinguishable, is called foetus. Animals which give birth to offspring are called viviparous; and the ones which develop through eggs are called oviparous.

QUESTION: 13

Consider the following pairs regarding reproduction and development of organisms.

1. Budding — Reproduction process in Amoeba.

2. Binary fission — Reproduction process in Hydra.

3. Metamorphosis — Transformation of the larva into an adult through drastic changes.

Which of the pairs given above are correctly matched?

Solution:
  • Like plants, animals too have two types of reproduction: 1. Sexual reproduction 2. Asexual reproduction The type of reproduction, wherein only one parent participates is called asexual reproduction.

  • Budding and binary fission are methods of reproduction. Hydra reproduces through budding, and amoeba reproduces through binary fission. The transformation of the larva into an adult through drastic changes is called metamorphosis.

QUESTION: 14

Consider the following statements regarding cloning:

1. It is the process of artificially developing a tissue or any other living part of an animal.

2. A sheep, Dolly was the first successfully cloned animal.

3. Dolly was a clone of the Finn Dorset Sheep.

Which of the statements given above is/are correct?

Solution:
  • Cloning is the production of an exact copy of a cell, any other living part, or a complete organism.Cloning of an animal was successfully performed for the first time by Ian Wilmut and his colleagues at the Roslin Institute in Edinburgh, Scotland.

  • During the process of cloning Dolly, a cell was collected from the mammary gland of a female Finn Dorset sheep. Simultaneously, an egg was obtained from a Scottish blackface ewe.

  • The nucleus was removed from the egg. Then, the nucleus of the mammary gland cell from the Finn Dorset sheep was inserted into the egg of the Scottish blackface ewe whose nucleus had been removed.

  • The egg thus produced was implanted into the Scottish blackface ewe. Development of this egg followed normally and finally Dolly was born.

QUESTION: 15

Consider the following statements regarding cell:

1. It is the smallest living part of any living organism.

2. The first cell was discovered by Antonie van Leeuwenhoek.

3. The smallest cell is bacteria and the largest is ostrich egg.

Which of the statements given above is/are correct?

Solution:

The smallest living part of any organism is called a cell. Hence, it is the structural unit of all organisms. Many cells together form the tissue, and tissue forms organs. The cells of cork were the first to be discovered in the year 1665; by Robert Hooke. Antonie van Leeuwenhoek was the first to discover bacteria. The smallest cell is the bacterial cell, and the largest is an ostrich egg; hence, statement 3 is correct.

 

 

QUESTION: 16

Consider the following statements:

1. Amoeba

2. Paramecium

3. Hen’s egg

4. White blood cells (WBCs)

Which of the above are examples of unicellular bodies?

Solution:
  • An organism consisting of one cell is called unicellular. Amoeba, paramecium, hen’s egg and White Blood Cells are all examples of unicellular organisms.

  • Organisms made up of more than one cell are called multicellular. In unicellular organisms, the single cell itself performs all the activities that multicellular organisms do, like respiration, growth, excretion, reproduction, etc; which are performed by groups of tissues in multicellular organisms.

QUESTION: 17

The basic components of a cell are cell membrane, cytoplasm and nucleus. Consider the following statements regarding these components of the cell:

1. Plasma membrane separates one cell from another and from the surrounding medium.

2. Cytoplasm is the jelly like substance found between the cell membrane and the nucleus.

3. Chromosomes are present in the nucleus.

Which of the statements given above is/are correct?

Solution:
  • Various components of the cell have a boundary, which is known as plasma membrane or cell membrane. This membrane separates one cell from another and also from the surrounding medium.

  • It is porous and allows various substances to enter the cell. This membrane [provides structure to the plant and animal cells. Cytoplasm is a jelly like substance, which is found between the cell membrane and nucleus.

  • The other components of the cell (mitochondria, golgi complex, ribosomes, etc) are found in the cytoplasm itself. Nuclei are circular in shape and present in the central region of the cytoplasm.

  • The nuclear membrane separates the nucleus from the cytoplasm. This nuclear membrane is also porous and regulates the incoming and outgoing of materials between the cytoplasm and the nucleus.

  • This nuclear membrane is absent in the bacterial cells. Nucleolus and chromosomes are present within the nucleus. Chromosomes are present within the nucleus. Chromosomes carry genes and can be seen only when the cell divides. These help in inheritance or transfer of characters from the parents to the offsprings.

QUESTION: 18

Consider the following statements regarding prokaryotic cells.

1. Nuclear membrane is absent in prokaryotic cells.

2. Virus and blue green algae are examples of the same.

Which of the above given statements/ statements is/are correct?

Solution:
  • The cells which do not have a well organised nucleus, are called prokaryotic cells. In contrast, cells with a well organised nucleus are called eukaryotic cells. Organisms with prokaryotic cells are called prokaryotes.

  • Bacteria and blue green algae are examples of the same. Viruses are neither prokaryotic, nor eukaryotic. Organisms with eukaryotic cells are called eukaryotes. Onion and human cells are examples of the same.

QUESTION: 19

Plant and animal cells are different from one another. Consider the following statements regarding these differences:

1. Animal cells, in contrast to the plant cells, have an additional boundary of the cell wall.

2. Plastids are found only in plant cells.

3. There are many small vacuoles in animal cells, whereas plant cells have one, central vacuole.

Which of the statements given above is/are correct?

Solution:
  • Animal cells are devoid of cell walls. Cell wall is present in plant cells, apart from the cell membrane. It provides rigidity and shape to the plant cell. Bacterial cells also possess cell walls. Plastids are found only in plant cells.

  • These are mostly variously coloured. Some of these have chlorophyll, which is a green pigment. Green plastids are called chloroplast, which provide green colour to the leaves. Animal cells have many small vacuoles and plant cells have one big, central vacuole. Hence, statement 3 is correct.

QUESTION: 20

Which of the following cells act as messengers?

Solution:
  • There are many types of cells in the human body, which differ in shape and labour. The function of receiving messages and transmitting is performed by nerve cells. These cells are long and branched.

  • Similarly, blood cells are circular and muscle cells are spindle shaped. In case of plant cells, amoeba is a cell which has an irregular shape. The irregular shape of amoeba results in the formation of pseudopodia, which provides it motion and helps in capturing food.

QUESTION: 21

Sex hormones are secreted by endocrine glands. Consider the following statements regarding the same.

1. Estrogen and testosterone are sex hormones. These are responsible for the secondary sexual characters in the human body.

2. Estrogen is the male hormone, while testosterone is the female hormone.

3. The secretion of these hormones is regulated by a separate hormone, secreted by the pituitary.

Which of the above given statements/statements is/are correct?

Solution:
  • Endocrine glands release hormones directly into the bloodstream, and hence are also called ductless glands. Sex hormones are also secreted through endocrine/ductless glands.

  • Estrogen and testosterone are sex hormones which are responsible for secondary sexual characters. Estrogen is the female hormone and testosterone is the male hormone, secreted by ovary in females and testes in males respectively.

  • This sex hormone is responsible for the development of facial hair, enlargement of voice box (larynx, Adam’s apple) etc in males.

  • Due to an enlarged voice box, boys have a deeper voice and girls have a high pitched voice. Secondary sexual characteristics like development of breasts and mammary glands in females is caused by estrogen.

  • The secretion of these sex hormones is regulated by a separate hormone, secreted by the pituitary. It regulates the maturation of egg/ovum in the ovary and sperms in the testes.

QUESTION: 22

Match the items given in column 1 with the items of column 2, and use the key given below.

Solution: Thyroxine, insulin and adrenaline are secreted by thyroid, pancreas and adrenal gland respectively. Pituitary gland secretes the growth hormone and stimulates the other endocrine glands- testes, ovary, thyroid and adrenal to secrete other hormones.

QUESTION: 23

Consider the following statements in context to the human body.

1. Milk is a complete meal in itself.

2. Iron rich meals help in the production of blood.

3. Fat is essential for the growth of the body and also for protein energy.

Which of the above given statement/statements is/are correct

Solution: A balanced diet means a diet with protein, carbohydrates, fats, vitamin and minerals in appropriate amounts. Indian diet consisting of rotis, rice, pulses and vegetables is a balanced diet; milk, in itself is a complete meal. Iron rich food, like leafy vegetables, jaggery, meat, tangerine, amla, etc are helpful in the production of blood. Fats and carbs are essential for energy and protein, for the growth of the body. Milk, meat, nuts and pulses are sources of protein.

QUESTION: 24

Of the forces given below, which is the example of a non-contact force?

1. Friction force

2. Magnetic force

3. Electrostatic force

4. Gravitational force

5. Muscular force

Solution: Magnetic force, electrostatic force and gravitational force are examples of non-contact forces. This force can act on objects, despite not being in contact with the same. Friction and muscular forces are examples of contact forces. These forces need to be in contact with the objects to act on them.

QUESTION: 25

Consider the following statements about gravitational force.

1. Gravitation is a property of only the earth.

2. All the objects of the universe apply gravitational force on each other.

3. Gravitational force is responsible for water in rivers to flow downstream.

Which of the above given statements/statements is/are correct?

Solution: Gravitation is not the property of only Earth. In reality, all the objects of the universe apply force on each other, regardless of their size. Gravitational force is responsible for the water in rivers to flow downstream.

QUESTION: 26

Consider the following statements

1. Wind moves from low pressure areas to high pressure areas.

2. Due to gravity the air at the surface is denser and hence has higher pressure.

Select the correct answer from the following codes

Solution: Due to gravity the air at the surface is denser and hence has higher pressure. The pressure decreases with height. Wind always moves from high pressure areas to low pressure areas.

QUESTION: 27

Which of the following is measured in Pa (Pascal)?

Solution: The amount of force exerted (thrust) on a surface per unit area is defined as ‘Pressure’. It can also be defined as the ratio of the force to the area (over which the force is acting). Example: It is easier to hammer a sharp pain than to hammer a blunt pin. This is because the area at the end of the sharp pin is smaller than the area at the end of a blunt pin. This leads to an increase in pressure leading to hammering the sharp pin easily.

Types of Pressure:

1. Atmospheric Pressure

2. Absolute Pressure

3. Differential Pressure

4. Gauge Pressure

QUESTION: 28

The number of chromosomes are present in human cells.

Solution:
  • Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA).

  • Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique. The term chromosome comes from the Greek words for color (chroma) and body (soma).

  • Scientists gave this name to chromosomes because they are cell structures, or bodies, that are strongly stained by some colorful dyes used in research. Humans have 23 pairs of chromosomes, for a total of 46 chromosomes.

  • In fact, each species of plants and animals has a set number of chromosomes. A fruit fly, for example, has four pairs of chromosomes, while a rice plant has 12 and a dog, 39.

QUESTION: 29

Puberty age in males is

Solution: Puberty usually occurs in girls between the ages of 10 and 14, while in boys it generally occurs later, between the ages of 12 and 16. In some African-American girls, puberty begins earlier, at about age 9, meaning that puberty occurs from ages 9 to 14.

QUESTION: 30

Force is defined as

Solution:
  • In science, force is the push or pull on an object with mass that causes it to change velocity (to accelerate).

  • Force represents a vector, which means it has both magnitude and direction. In equations and diagrams, a force is usually denoted by the symbol F.

  • An example is an equation from Newton's second law: F = m·a where F = force, m = mass, and a = acceleration. Units of Force The SI unit of force is the newton (N).

  • Other units of force include.

    • dyne

    • kilogram-force (kilopond)

    • poundal

    • pound-force