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ScienceClass 8CBSE

What do black buck, elephant, python and golden cat together represent in a forest? (a) fauna (b) flora (c) ecosystem species

Soln: Answer is (a) fauna Explanation: Fauna is the animals in a particular area. Flora is the plant species in a particular area. Ecosystem includes physical environment along with plants and animals of a particular area. Species is a group of inbreeding population.

ScienceClass 8CBSE

Which statement is incorrect about endangered species? (a) Their number has decreased drastically. (b) They might become extinct in the near future. (c) They pose a danger to other animals. Their natural habitat needs to be protected

Soln: Answer is (c) They pose a danger to other animals.

ScienceClass 8CBSE

Which of the following feature is correct for a wildlife sanctuary? (a) It is an artificially created protected area for animals. (b) It is a protected area for threatened and endangered wild animals. (c) It is meant for conservation of only plant species. (d) Capturing and poaching of animals is strictly prohibited here.

Soln: Answer is (a) It is an artificially created protected area for animals. Explanation: Wild life sanctuary is an artificially created protected area for animals. Hence option c) is wrong . Wild life sanctuaries are not specific for threatened and endangered wild animals. Hence answer b) is wrong. Capturing and poaching of animals is strictly prohibited everywhere hence option d) is not appropriate.

ScienceClass 8CBSE

Which one of the following statements is true about endemic species? (a) They are found exclusively in a specific habitat. (b) Endemic species can never become endangered. (c) They are found only in zoos and botanical gardens. (d) They are not affected by the destruction of their habitat.

Soln: Answer is (a) They are found exclusively in a specific habitat. Explanation: Endemic species are those which are found exclusively in a specific habitat. Endemic species get extinct when habitat is destroyed by human activities or by introduction of new species is introduced to the habitat.

ScienceClass 8CBSE

The place meant for conservation of biodiversity in their natural habitat are (i) Zoological garden (ii) Botanical garden (iii) Wildlife sanctuary (iv) National park (a) i & ii; (b) ii & iii; (c) iii & iv; i & iv

Answer is (c) iii & iv; Explanation: In botanical garden and zoological parks species are protect outside their natural habitat and its ex-situ conservation. On the other hand Wildlife sanctuary and National park are in-situ conservation where conservation of biodiversity occurs in their natural habitat.

ScienceClass 8CBSE

Which one of the following statements is true about a Biosphere Reserve? (a) It is a protected area where only endemic species live. (b) It is meant only for the conservation of plants and animals. (c) It is meant to conserve both, the biodiversity and the culture of that area. (d) There are no other protected areas within its limits.

Answer is (c) It is meant to conserve both, the biodiversity and the culture of that area. Explanation: Biosphere reserve is the protected part of land covered with forests. It is meant for the conservation of wild life, biodiversity and traditional lifestyle of tribals.

ScienceClass 8CBSE

Which one of the following changes may occur due to desertification? (a) Decrease in atmospheric temperature. (b) Increase in water holding capacity of soil. (c) Increased chances of floods. (d) Conversion of fertile land into a desert.

Answer is (d) Conversion of fertile land into a desert. Explanation: Soil is carried away by wind when there are no trees as there will be no roots to hold onto the soil. Thus top soil erodes out which will turn the land to desert.

ScienceClass 8CBSE

Wild buffalo is an endangered species because (a) its population is diminishing (b) it has become extinct (c) it is found exclusively in a particular area its poaching is strictly prohibited

Answer is (a) its population is diminishing Explanation: Endangered species are those whose population is diminishing at an alarming rate and they may face extinction in near future.

ScienceClass 8CBSE

Hens and frogs are both oviparous exhibiting different types of fertilisation. Explain.

In Hens internal fertilisation takes place. Fertilised egg develops inside female body but development of chick from the embryo takes place outside the body. On the other hand in frogs both fertilisation and development of zygote to embryo and young ones occurs outside the body.

ScienceClass 8CBSE

Why do only male gametes have a tail?

Because sperm need to be motile to reach non-motile egg in the ovary of female.

ScienceClass 8CBSE

State whether the following statements are True or False. If false, correct the statement: (a) External fertilisation can occur both in water and on land. (b) The eggs of fish are covered by hard shells for protection. (c) Human egg has a head, middle piece and tail. (d) In adult human females, a single mature egg is released into an oviduct every month.

False- External fertilisation can occur only in False- eggs of fish are covered by jelly like substance for False- Human sperm has a head, middle piece and True

ScienceClass 8CBSE

How is reproduction in hydra different from that in amoeba?

Hydra reproduce by budding where a bud detacthes from the parent which grows into complete organism. Whereas amoeba reproduces by binary fission. The process of reproduction begins by the division of its nucleus into two. This is followed by the division of its body into two.

ScienceClass 8CBSE

Mother gives birth to a baby but the baby has characters of both parents. How is this possible?

Though mother gives birth to a baby but fertilization involves fusion of gametes from both the parents. Hence character are obtained by both the parents.

ScienceClass 8CBSE

The term metamorphosis is not used while describing human development. Why?

Because body parts of humans will be present by birth. Whereas in metamorphosis parts of adults are different from the young ones.

ScienceClass 8CBSE

The eggs of frogs do not have shells for protection, yet they are safe in water. How?

Jelly like covering on the eggs give the protection Hence frog’s eggs are safe in water

ScienceClass 8CBSE

In markets, eggs of birds are available but never eggs of dogs. Why?

Because dog is vivaparous. It does not lay egg. It gives birth to a new one.

ScienceClass 8CBSE

What is the importance of reproduction?

Soln: Reproduction ensures continuation of species from generation to generation.

ScienceClass 8CBSE

Although 2 cells called gametes fuse, the product formed is a single cell called zygote. Justify.

During fertilization only nucleus of the sperm gets implanted into uterus to form zygote. Then sperm degenerates. Hence fused cell is called gamete. Stages in the lifecycle of silkworm are given below. Write them in sequential order.

ScienceClass 8CBSE

In human beings, the correct sequence of events during reproduction is (a) gamete formation, fertilisation, zygote, embryo (b) embryo, zygote, fertilisation, gamete formation (c) fertilisation, gamete formation, embryo, zygote gamete formation, fertilisation, embryo, zygote

Soln: Answer is (a) gamete formation, fertilisation, zygote, embryo Explanation: In humans male gametes fuse with female gametes to fertilise in the female ovary. Fertilised sperm and egg form zygote which will divide repeatedly to form the embryo.

ScienceClass 8CBSE

After fertilisation, the resulting cell which gives rise to a new individual is the (a) embryo (b) ovum (c) foetus zygote

Soln: Answer is (d) zygote Explanation: Zygote is the beginning of formation of a new individual. All the multicellular organisms start their life from single celled zygote.

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