Blog Archives

10th Biology:HEREDITY AND EVOLUTION SOLVED

24/2/2013

HEREDITY AND EVOLUTION SOLVED EXERCISES QUESTIONS [Biology Term-2 CHAPTER - 13]
VERY SHORT ANSWER QUESTIONS (1 mark)
1. Who proposed the theory of inheritance of acquired characters.

Answer: J.B. Lamarck.

2. State one of the evolutionary forces leading to the origin of a new species according to the synthetic theory of evolution.

Answer: Origin of new species is based on natural selection acting on genetic variations that appear among the members of a population.

3. Give an example of a vestigial organ present in human body.

Answer: Vermiform appendix.

4. What is the evolutionary significance of the fossil Archaeopteryx?

Answer: Archaeopteryx is the connecting link between reptiles and birds. It has both reptilian on features and avian(bird-like) features.

5. Who proposed the double helical model of DNA?

Answer: Watson and Crick.

6. Who proposed the theory of natural selection?

Answer: Charles Darwin.

7. What is retro virus?

Answer: A virus with RNA as the genetic material eg: HIV is a retro virus.

8. What is a genetically modified organism (GMO)?

Answer: The organism that contains a segment of foreign DNA.

9. Name any two genetic diseases.

Answer: Hemophilia and colour blindness.

10. One of the examples of two analogous organs can be the wing of parrot and
a) Flippers of whale.
c)Foreleg of horse
b) Front leg of frog
d)Wing of housefly

Answer: Wing of housefly

SHORT ANSWER QUESTIONS (2 marks)

1. What are transgenic organisms? Which property of DNA is used as a tool in genetic engineering?

Answer: The organisms that contain a segment of foreign DNA are known as transgenic organisms.The complimentary property of the nucleotides of DNA.is the most powerful tool in genetic engineering.

2. Explain how the sex of the child is determined at the time of conception in human beings.
Answer: Male human beings have XY sex-chromosomes and female human beings have XX sex-chromosomes. If a sperm carrying x-chromosome fertilizes with the ovum, then sex of the baby will be female. If a sperm carrying y-chromosome fuses with the ovum, the sex of the baby will be male.

3. By comparing the similarity of nucleotide sequences in DNA of different kinds of organisms, evolutionary relationships can be established.

a) Arrange the following according to their evolutionary closeness (You may use your knowledge of classification also) Cockroach, mango tree, gorilla, fish.

b) Whose DNA among the following do you think is most similar to that of humans.

Answer: (a) cockroach – fish – gorilla
( b) Gorilla

4. Mention the ways by which variant genotypes are produced in organism?
Answer: a) gene mutation b) Crossing over c) Hybridization

5. In human beings blue eye colour is recessive to brown eye colour . If a brown eyed man has a blue eyed mother then find
a) What are the possible genotypes of his father?
b) What is the genotype of the man and his mother?
Answer: BB , Bb B. Man: Bb, mother: bb

6. What are fossils? Of what interest are fossils to the evolutionary biologists?

Answer: A fossil is the remnant or impression of an organism that lived in the Remote past.

Use of Fossils
a) Phylogeny, the evolutionary history can be reconstructed from the fossils.
b) The fossil record has helped in building the broad historical sequence of biological evolution.

SHORT ANSWER QUESTION (3 marks)

1. a) Who isolated DNA for the first time from pus cells?
b) Why is DNA called polynucleotide?
c) Name two purine nitrogenous bases found in a DNA molecule.

Answer: a) F.Meishcer, named it nuclein. b)DNA is called polynucleolide because it is a polymer or long chain of nucleolide.
c)Purine:- Adenine and Guanine.

2. a) Who put forward the double helical model of DNA?
b) What are the three chemically essential parts of nucleotides constituting a DNA?

Answer:  a) Watson and Crick.

b)Nucleotide constituting –DNA Nitrogen bases (Purines and Pyrimidines), Pentose sugar(Deoxyribose sugar) and a phosphate molecule.

3.Guinea pig having black colour when crossed with guinea pig having same colour produced 80 offspring, out of which 60 were black and 20 were white. Now,find out:

a)What is the possible genotype of the guinea pigs?

b)Which trait is dominant and which trait is recessive? c)What is this cross called as and what is its phenotypic ratio?

Answer:
a) Bb x Bb
b)Black is dominant and white is recessive.
c) Monohybrid cross, phenotypic ratio=3:1

4. Write a brief account on . Who disproved this theory?

Answer: salient points of Lamarck‘s theory:
1.The use and disuse of an organ leads to acquiring of change in the features of that organ.
2. These changes are inherited by the offspring.
3. Favourable variations result in evolution of new species.

August Weisman disproved this theory.

5. Distinguish between acquired and inherited traits giving one example of each.

Answer:
Acquired traits
1) A trait (or characteristic) of a organism which is not inherited‘ but develops in response to the environment is called an acquired trait.
(2) The acquired traits of an organism cannot be passed on to its future generations. e.g. low weight‘ of beetle, cut tail‘ of a mouse.
Inherited traits
1) A trait (or characteristic) of an organism which is caused by a change in its genes (or DNA) is called an inherited trait.
2) The inherited traits of an organism are passed on to its future generations. e.g. red colour of beetles, fur coat of guinea pigs.

6. Why did Mendel chosen pea plant for his experiments? T-II 2015

Answer:   Mendel chose pea plant for his experiments because it is:
(a) Easy to grow
(b) Short lifespan
(c) Easily distinguishable characters
(d) Larger size of flower (e) Self-pollinated.

HEREDITY AND EVOLUTION [SOLVED][Biology Term-2] Click Here

10th Science SA-2 Chapter wise Test Papers Links
1. Carbon and Its Compounds
6. The Human Eye and the Colorful World
2. Periodic Classification of Elements
7. Our Environment
3. How Do Organisms Reproduce?
8. Management of Natural Resource
4. Heredity and Evolution
9. Science Sample papers
5. Light - Reflection and Refraction
10. X Science NCERT SOLUTIONS

14 Comments

10th Biology Guess Paper Solved for CBSE[SA-II]

20/2/2013

1 Comment

Q. What are the different ways in which individuals with a particular trait may increase in a population?

Answer: The different ways in which individuals with a particular trait may increase in a population are following :

􀁑 Food availability – Individuals with a particular trait may have extra abundance of food in their environment. They will naturally increase in number.

􀁑 Genetic drift – Individuals with a particular trait may increase in a population due to genetic drift. In it, there is a seasonal or accidental decline in population. The survivors have certain combination of traits which increase in number with increase in population

􀁑 Natural selection – The particular trait which has survival value is picked up by natural selection. It increases in population through differential reproduction.

Q. What do they tell us about the process of evolution?

Answer: Fossils provide a direct evidence of evolution and are called written documents of evolution. They directly indicate the presence of different types of organisms in different ages.

The path of evolution is known by arranging the fossils in a proper sequence age wise. The early fossils are the simple organisms. Later on different complex forms arose, flourished and died down. They are replaced by newer forms.

Q. state the analogy between wings of a bird and a butterfly. What does it indicate?

Answer: They are analogous because both bats and birds adapted to flight. Bat being a mammal has the finger extension type wing and bird being aves with the full forelimb extending the wing. As structure both the wings are different, so are considered as analogous organ.

Q. Why did Mendel choose pea plant for his experiments?

Answer: Mendel chooses pea plant because:

a.    Presence of observable traits with contrasting forms.

b.    Produces many offspring in one cross.

c.    Short life cycle.

d.    Ease in cross pollination.

e.    Plants were sexually reproducing with bisexual flowers.

f.     Hybrids were perfectly fertile

Q. Why is vegetative propagation practiced for growing some types of plants?

Answer: Vegetative propagation is generally performed in higher plants of ornamental, horticultural, medicinal and other economic importance. It is practiced for growing these plants because

(i) Good qualities of a variety can be maintained indefinitely.

(ii) Vegetative propagation gives a genetically uniform population.

(iii) Vegetative propagation is a quicker method of raising of crops.

(iv) It is the only known method of multiplication of seedless plants

Q. Leaves of Bryophyllum fallen on the ground produce new plants whereas the leaves of Jasmine do not, why?

Answer:   In Bryophyllum, vegetative propagation occurs through leaves. Buds occur in notches of Bryophyllum leaf. However, when the leaf falls down and comes in contact with the soil, the buds spout and produce plantlets.

Q. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem? Where will the magnification maximum?

Solution : The accumulation of harmful chemicals in the body of living organisms at different trophic levels in a food chain is called biological magnification.

Yes, the concentration of these harmful chemicals will be different at different levels of the ecosystem.

It will be maximum at the last trophic level which is mostly the top carnivores (quaternary consumers).

Q. What are analogous organs? Explain with examples.

Solution: The organs which are similar in function or appearance but differ in structure and development are called analogous organs.

The wings of a bird and an insect are developmentally and structurally different from each other. Skeleton, flesh and feathers support bird's wings. The insects have a fold of membrane as wing, which is associated with few muscles. Wings of birds and insects are structurally different but perform the same function of flying. They are therefore, termed as analogous organs.

Q. Mrs. Kumar is pregnant for the last three months and she goes for regular check-up to her doctor. During her last visit, the doctor asked Mrs. Kumar to get an ultrasound done. Both Mr. and Mrs. Kumar went to a radiologist and got the ultrasound done. Once the ultrasound is over, Mr. Kumar asked the doctor whether the baby in the womb is a boy or a girl.
(a) What should the doctor reply to the couple?
(b) Is it ethical to determine the sex of a child?
(c) What should government do to discourage sex determination?

Solution : (a) The doctor should not tell the sex of the foetus.

(b) No, it is not ethical to determine the sex of a child.

(c) The government should ban the process of sex determination and should punish or fine whosoever does so.

Q. (a) Why is vegetative propagation practised for growing some types of plants?
(b) Name the different parts of a flower that has germ cells.
(c) List any two agents of pollination.

Answer: (a) Some plants like banana, seedless grapes, rose, which cannot produce viable seeds, can be easily grown by vegetative propagation. To get genetically identical copies and to maintain and preserve a stock of selected varieties, vegetative propagation is the only means. It is an easier less expensive and rapid method of propagation
(b) Style and ovule both have germ cells.
(c) Wind and water

Q. What happens to the pollen which falls on a suitable stigma? Explain.

Answer: The pollen grains absorb water and sugar from the surface of stigma and swell up. A tube grows out of the pollen grain and travel through the style to reach the ovary. The pollen tube carrying two male gametes which liberated inside the embryo sac. One male gamete fuses with the egg to form zygote. The other male gamete fuses with the secondary nucleus to form the endosperm, which provides nourishment to the growing embryo.

Q.How many 'X' chromosomes are present in body cells of humans in a:
(i) Male (ii) Female?
(iii) Describe the role of sex chromosomes in deciding the sex of the child.

Solution : (i) In the body cells of human males one X and one Y chromosome is present. 50 percent male gametes (sperms) carry X-chromosome and the remaining 50 percent carry Y-chromosome.

(ii) The body cells of human female carry two X-chromosomes. Females produce gametes (ova) with similar type of chromosomes, all carry one X-chromosome.

(iii) Sex chromosomes in males are XY type while in female they are XX type. When a sperm carrying X- chromosome fertilizes an egg, the zygote develops into a female (XX condition). When sperm carrying Y chromosome fertilizes an egg, the zygote develops into a male (XY condition).

Q. What is meant by tissue culture? How this technique is performed? In which area this technique is finding its application.

Solution : The production of plants by cells or tissues or organs in a synthetic medium is called tissue culture. This technique is also Know as micro propagation technique. The synthetic medium used in this technique contains all the nutrients and hormones which are required for the growth.

A cell or tissue is transferred into suitable synthetic medium under sterile conditions. The tissue often develops into a fast growing cellular mass called callus. The callus is transferred to another medium for growth and differentiation that forms plantlets. The plantlets can be transplanted into soil or pots where they can be grown to maturity. Tissue culture technique is being popularly used for production of ornamental plants like Orchids, Dahlia and Carnation.

1 Comment

6th Science practice questions Air around Us

19/2/2013

11 Comments

[1] Fill in the blanks :- [Practice Questions For Chapter: Air around Us ]

1. Air occupies _________________________.

2. Harmful gases and smoke in the air causes _________________________.

3. The _______________________ and ______________________ within the nasal passage prevents entry of dust particles into our respiratory system.

4. Air helps in _________________________ of sound.

6. Air is really not one substance but a __________________.

7. The component of air that supports burning is called ________________.

8. The aquatic animals use dissolved Oxygen in water for respiration, this is possible because Oxygen ________________ in water.

9. Nitrogen of the air is used on a large scale to manufacture ________________.

10. ________________ is the place in nature for gaseous exchange.

[2] Choose the correct answer :-

1. The height of the atmosphere is (120 km/240km)

2. The volume of oxygen (increases/decreases) with increase in altitudes.

3. (Carbondioxide/Oxygen) is taken in by the plants for photosynthesis.

4. Air contain approximately (78 percent/80 percent) of Nitrogen.

[3] II. True or False statements :

1. Air is a compound but not an element.

2. Air is an opaque material.

3. Air contains water vapour.

4. The major part of air is Nitrogen.

5. Plants produce Oxygen through photosynthesis.

[4] Name the following :-

1. The two scientists who proved air is a mixture of gases :

2. The lightest gas in the air.

3. The gas essential for combustion and respiration.

4. The substance in presence of which photosynthesis takes place :

[5] Define the following :-

(a) Atmosphere

(b) Respiration

11 Comments

Class 6th Chapter-(Garbage In, Garbage Out ,Waste) [CBSE Assignments]

18/2/2013

4 Comments

Answer these Questions

1. How do earthworms increase fertility of soil?

2. Rag pickers always suffer from diseases why?

3. Why does composting of leaves better than burning them?

4. Why should plastic food containers be avoided?

5. Why we should not throw away any things that can be recycled?

6. Why recycled plastic are not recommended for storing food in?

8. What is waste management and why it is so important?

9. Which garden worm generally used for Vermi composting.

10. Why worm box aerated in the process of vermi composting?

11. Fill in the blanks:

a ._______ is generated in homes, industries, agricultural fields and in other human activities. This is called _______.

b. Sewage is a liquid waste which causes ______ and ____ pollution.

c. Wastewater is treated in _______ treatment plant.

d. By-products of wastewater treatment are ______ and _______.

e. ________ of water can be removed by boiling it or treating it with washing soda.

f. Cleaning of waste water is commonly known as ________.

Ans: a. waste water sewage. b. water, soil. c. sewage. d. sludge, biogas. e. hardness. f. sewage treatment.
Related Post
Class 6th Chapter-Waste (Garbage In, Garbage Out )...6th Science View

4 Comments

8th Pollution of Air and Water [Science Solution]

17/2/2013

9 Comments

Q.1 Fill in the blanks:-

(i) By volume about _______ of air is nitrogen and about _________ is oxygen.

[78% ,21% ]

(ii) Incomplete burning of fuels produces ________ which is a _______ gas.

[carbon mono oxide, poisonous]

(iii) Carbon monoxide _________ the oxygen carrying capacity of the blood.

[Reduce]

(iv) Petroleum refineries are a major source of gaseous pollutants like ______ and ______.

[sulphur dioxide and nitrogen dioxide.]

(v) _______ used in refrigerators damages the ozone layer of the atmosphere.

[ chlorofluorocarbons]

(vi) Ozone layer protects us from the harmful ________ rays of the sun.

[Ultra Violet ]

(vii) _______ of the world’s population is without safe drinking water.

[25%]

(viii) We can save water by remembering the 3R’s ____, ____ and ________.

[Reduce, reuse and recycle]

(ix) Acid rain is formed by the oxidation followed by dissolution of ________ and gases in rain water.

[water vapour]

Q.2. Define air pollution. What are air pollutants?

Ans: When air is contaminated by unwanted substances which have a harmful effect on both the living and

the non-living, it is referred to as air pollution. The substances which contaminate the air are called air pollutants.

Q.3. what are the various sources of air pollutants?

Ans: Natural sources like smoke and dust arising from forest fires or volcanic eruptions. Human activity like factories, power plants, automobile exhausts and burning of firewood and dung cakes.

Q.4. what is smog? Why is it harmful?

Ans: A thick fog-like layer in the atmosphere, especially during winters. This is smog which is made up of smoke and fog. The smog causes breathing difficulties such as asthma, cough and wheezing in children.

Q.5. What is acid rain?

Ans: Sulphur dioxide and nitrogen dioxide react with the water vapour present in the atmosphere to form sulphuric acid and nitric acid. The acids drop down with rain, making the rain acidic. This is called acid rain.

Q.6 How is the Taj Mahal affected by air pollution?

Ans: Pollutants in air are discolouring its white marble.

Q.7 What is meant by ‘Marble Cancer’?

Ans: Acid rain corrodes the marble of the monument. The phenomenon is also called “Marble cancer”.

Q.8 Write the full forms (i) CFC (ii) CNG (iii) LPG (iv) WWF

Ans:(i) chlorofluorocarbons(ii)Compress natural gas(iii) Liquefied petroleum gas(iv) World Wide Fund

Q.9 what is greenhouse effect? Name four greenhouse gases.

Ans: A part of the radiation that falls on the earth is absorbed by it. The trapped radiations further warm the green house earth. This is called the greenhouse effect. CO2 ,CH4 , N2 O, SO2

Q.10 Write a note on global warming.

Ans: Greenhouse gases like CO2 traps Sun’s heat and does not allow it to escape into space. As a result, the average temperature of the earth’s atmosphere is gradually increasing. This is called global warming.

Q.11 What is Van Mahotsav?

Ans: Van Mahotsav is an annual tree-planting festival in India, celebrated in the first week of November.

Q.12 Why does the increased level of nutrients in the water affect the survival of aquatic organisms?

Ans: The increased level of nutrients in the water, enhance the growth of algae in the water body. Once the algae dies, they serve as food for decomposers like bacteria. For the decomposition, a lot of O2 in the water body decreases and may kill aquatic organisms.

Q.13 Why do we say that the river Ganga is dead at many places?

Ans: This is because the pollution levels are so high that aquatic life cannot survive.

Q.14 What is potable water?

Ans: Water which is suitable for drinking is called potable water

Q.15. What are the various methods by which water can be made safe for drinking?

Ans: The various methods by which water can be made safe for drinking are: (a) Using candle type filter (ii) boiling (iii) by adding chlorine tablets or bleaching powder to the water

9 Comments

8th Conservation of Plants and Animals[Questions with Solution]

17/2/2013

20 Comments

1 mark Questions

1. A place where animals are protected in their natural habitat is called a _____________ .

Ans: sanctuary.

2. Species found only in a particular area are known as ______.

Ans: Endemic species

3. Migratory birds fly to far away places because of ____ _ changes.

Ans: Weather /climatic

4. ___________ National Park is the first Reserve Forest of India where the finest Indian teak is found.

Ans: Satpura National

5. A group of populations which are capable of interbreeding is called d_______________

Ans: Species

4. Differentiate between the following:

(i) Wildlife sanctuary and biosphere reserve

Ans: Biosphere Reserve : Large areas of protected land for conservation of wild life, plant and animal resources and traditional life of the tribals living in the area.

Wildlife sanctuary: Areas where animals are protected from any disturbance to them and their habitat.

(ii) Zoo and wildlife sanctuary

Ans: The zoo keeps animals in captivity, within artificially created habitat, whereas the sanctuary provides home to animals in their natural habitat without captivity.

(iii) Endangered and extinct species

Ans: Animals whose numbers are diminishing to a level that they might face extinction are known as the endangered animal e.g. Tiger where as a species that has completely disappeared from the planet like the pink-headed duck and the cheetah is called extinct species

(iv) Flora and fauna

Ans: All the different kinds of plants on earth constitute its flora and all its different kinds of animals are collectively called its fauna.

2 marks Questions

1. How does deforestation reduce rainfall on land?

Ans: Since plants help in evaporation of water , deforestation reduce rainfall on land.

2. How does deforestation led to floods on the land?

Ans: Deforestation also leads to a decrease in the water holding capacity of the soil. The movement of water from the soil surface into the ground (infiltration rate) is reduced. So, there are floods

3. What is the purpose of making national parks, wildlife sanctuaries and biosphere reserves?

Ans: The purpose of making national parks, wildlife sanctuaries and biosphere reserves is to conserve and protect the whole ecosystem from exploitation and to protect the ecosystem.

3 mark Questions.

1. Why should we conserve biodiversity?

Ans: This is because Biodiversity maintains the environment around us. Plants and animals together maintain several natural cycles such as the oxygen, nitrogen and carbon cycles. These gases in turn play a crucial role in maintaining life on earth.

2. Protected forests are also not completely safe for wild animals. Why?

Ans: It is a pity that even protected forests are not safe because people living in the neighborhood encroach upon them and destroy them.

3. Some tribal’s depend on the jungle. How?

Ans: Some tribals depend on the jungle as they live in the deep forest like primitive people had lived in ancient time. They are still away from the basic amenities of modern life Forest provide them food items like seed grains, fruit, raw vegetables and other products like honey, meat of hunted wild animals for themselves, fodder for theirs animals, wood fuel for heating and cooking even clothing using natural fibres, leaves and animal skins.

4. What are the causes and consequences of deforestation?

Ans: The main causes of deforestation are uses of forest resources by the human being to meet the growing demand of population, rapid urbanization, and industrialization. Some natural causes of deforestation are forest fires and severe droughts.

The consequences of deforestation are: (a) Increase in carbon dioxide level in the air. (b) Increase in temperature and pollution level on earth. (c) Lowering in ground water level. (d) More chances of natural calamities like floods and droughts. (e) Soil erosion leading to loss of humus and fertility of the top soil. (f) Desertification of large areas and (g) Decrease in water holding capacity and nutrient content of the soil.

5. What is Red Data Book?

Ans: Red Data Book is the source book which keeps a record of all the endangered animals and plants

6. What do you understand by the term migration?

Ans: Migration is the phenomenon of movement of a species from its own habitat to some other habitat for a particular time period every year for a specific purpose like breeding.

5 marks Questions

1. In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut trees for such projects? Discuss and prepare a brief report.

Ans: Yes, cutting trees for shelter and supply in factories is proper and justified. But equal number (or more) of trees should be replanted so that the land remains covered with trees and there is least damage to the environment and natural habitat of wild animals.

2. How can you contribute to the maintenance of green wealth of your locality? Make a list of actions to be taken by you.

Ans: We can help in maintaining the green wealth of our locality by following ways

(a) By planting as many trees as possible in open unused land (b) By reducing use of trees for firewood and other purposes.(c) Recycling and reuse of paper (d) wood should be done to avoid cutting of wood.

3. Why should paper be saved? Prepare a list of ways by which you can save paper.

Ans: Paper is made from the pulp of wood. Production of paper on a large scale needs regular supply of trees. This causes deforestation of large areas of land. So, we should save paper.

Paper can be saved by: (a) Recycling of used paper. (b) Reusing paper- Note books of previous year having blank pages should be used as rough copies (c) Wastage of paper for fun should be avoided.

4. What will happen if the habitat of an animal is disturbed?

Ans: If the natural habitat of animals is disturbed or destroyed, natural balance in the ecosystem will get disturbed and many animals will get extinct. The animals will not be able to live freely in their habitat.

5. Discuss the effects of deforestation on the next generation:

Ans: Deforestation increases pollution of air, global warming, reduces rainfall, decrease in ground water level and soil erosion. These problems will be faced by the next generations and will go on increasing.

Less rainfall will lead to less food production in the farms. Prices of food items will increase very high. Next generations will also face shortage of fresh water and unfavorable climate change due to deforestation.

20 Comments

ASSIGNMENT- CLASS 8-BIOLOGY- REPRODUCTION IN ANIMALS

14/2/2013

7 Comments

1. Explain the following terms:-
(a) Reproduction- The process of giving rise to new organisms of the same species.
(b) Fertilization-The fusion of male & female gametes.
(c) Zygote- The single-celled structure formed on the fusion of male & female gametes.
(d) Metamorphosis- The gradual transformation of an organism from one form to another during its life cycle
(e) Hermaphrodites-The organisms having both male & female reproductive organs in the same body. Eg:- Earthworm, Leech
(f) Foetus- The multicellular structure formed after the repeated cell divisions in the Zygote formed as a result of fertilization.
(g) Larva- The active form that emerges from the eggs .
(h) Placenta- The specialized tissue that attaches the developing foetus to the uterine wall & provides for it nourishment, respiration & excretion.

2. Give reasons for the following:-
(a) Gender of the resulting offspring is determined by the male parent in humans.
Ans- The Y-chromosome bearing sperm that fertilizes an ovum results in a male offspring.
The X-chromosome bearing sperm that fertilizes an ovum results in a female offspring.
(b) Sex hormones regulate secondary sexual characters.
Ans- The functioning of our reproductive organs is regulated by the sex hormones and one of the functions is the appearance of secondary sexual characters at puberty.
(c) Platypus & Echidna lay eggs but are not oviparous animals.
Ans- They lay eggs but feed the young ones on milk through the mammary glands.
(d) Sperm needs to have motility.
Ans – Sperms have to enter the female reproductive passage and fertilize the ovum by travelling through the vagina & uterus for this in the fallopian tube/ oviduct.

LONG ANSWER TYPE QUESTIONS:-

1. Explain where the embryo stays till it is fully developed and also explain how its nutritional , respiratory & excretory functions are carried out.
Ans- The embryo gets attached to the uterine wall through the Placenta which is a specialized tissue richly supplied by blood & takes care of all the developmental functions of the developing embryo- nutrition, respiration & excretion.
2. What is Asexual reproduction? What are the advantages of this method?
Ans- The mode of reproduction that involves a single organisms & also doesn’t require any special organs or cells. Its advantages are:-
(a) Offsprings produced are identical to the parents so desired traits can be transmitted to the next generation
(b) A quick method of reproduction
(c) Only one parent organism is required, no special organs or cells also required.
3. Explain the meaning of Binary Fission. Name a few organisms that reproduce like this & draw a series of diagrams to demonstrate this process in Amoeba.
Ans- The method by which an organism divides into two equal halves .
Other organisms are:- Paramecium, Euglena, Bacteria. Refer to figure 9.12 of NCERT
4. Explain how budding occurs. Name a few organisms that reproduce like this & draw a series of diagrams to demonstrate this process in Hydra.
Ans- Small bulges appear on the sides of the body of the organisms that gradually develop into new organisms. Sponges & Yeast besides Hydra.
Refer to figure 9.11 of NCERT
5. What is Metamorphosis? With the help of flow diagrams illustrate the life cycles of a Silkworm & Frog.
Ans- Metamorphosis- The gradual transformation of an organism from one form to another during its life cycle.
Silkworm:- Egg -->Larva/ Caterpillar--->Pupa/ Cocoon---> Adullt
Frog:- Egg---> Tadpole(Larva)- --> Froglet- --> Adult Frog

7 Comments

Three Dimensional Figures for class 8th Maths

9/2/2013

3 Comments

Points to Remember: Plane shapes having two measurements like length and breadth are called two dimensional shapes (2-D).
Solid shapes having three measurements like length, breadth and height or depth are called three dimensional shapes (3-D).
In polyhedron relationship between no. of faces (F), vertices (V) and edges (E) is F + V – E = 2 It is also called Euler’s Formula.
Prism : A polyhedron whose base and top are congruent polygon and whose other faces are parallelogram.
Pyramid : A polyhedron whose base is a polygon and whose lateral faces are triangles with a common vertex.
Practice Worksheet
1. Write down the number of faces of each of the following figures:
(i) Cuboid (ii) Cube (iii) Triangular prism (iv) Square pyramid      (v) Tetrahedron
2. Write down the number of edges of each of the following figures:
(i) Tetrahedron (ii) Rectangular pyramid (iii) Cube (iv) Triangular prism
3. Write down the number of vertices of each of the following figures:
(i) Cuboid (ii) Square pyramid (iii) Tetrahedron             (iv) Triangular prism
4. Fill in the blanks:
(i) A cube has …………….. vertices, …………….. edges and …………….. faces.
(ii) The point at which three faces of a figure meet is known as its …………….. .
(iii) A cuboid is also known as a rectangular …………….. .
(iv) A triangular pyramid is called a …………….. .
Answers:
1. (i) 6                    (ii) 6                    (iii) 5                      (iv) 5                    (v) 4
2. (i) 6                      (ii) 8                   (iii) 12                 (iv) 9
3. (i) 8                    (ii) 5                     (iii) 4                      (iv) 6
4. (i) 8, 12, 6        (ii) vertex          (iii) prism             (iv) tetrahedron

3 Comments

8th parallelogram worksheet and Assignments

9/2/2013

0 Comments

Q. Name each of the following parallelograms.

(i) The diagonals are equal and the adjacent sides are unequal.

(ii) The diagonals are equal and the adjacent sides are equal.

(iii) The diagonals are unequal and the adjacent sides are equal.

(iv) All the sides are equal and one angle is 60°.

(v) All the sides are equal and one angle is 90°.

(vi) All the angles are equal and the adjacent sides are unequal.

Ans: (i) rectangle (ii) square (iii) rhombus (iv) rhombus (v) square (vi) rectangle

Q. State whether True or False.

a) All rectangles are squares
Answer: All squares are rectangles but all rectangles can’t be squares, so this statement is false.

(b) All kites are rhombuses.
Answer: All rhombuses are kites but all kites can’t be rhombus

(c) All rhombuses are parallelograms
Answer: True

(d) All rhombuses are kites.
Answer: True

(e) All squares are rhombuses and also rectangles
Answer: True; squares fulfill all criteria of being a rectangle because all angles are right angle and opposite sides are equal. Similarly, they fulfill all criteria of a rhombus, as all sides are equal and their diagonals bisect each other.

(f) All parallelograms are trapeziums.
Answer: False;
All trapeziums are parallelograms, but all parallelograms can’t be trapezoid.

(g) All squares are not parallelograms.
Answer: False; all squares are parallelograms

(h) All squares are trapeziums.
Answer: True
For pdf Files Download
8th MCQ Parallelograms and quadrilaterals
8th Parallelogram solved Extra Edugain Questions
VIII Unsolved Extra Edugain Questions
8th Quadrilateral and Parallelogram Guess Questions
Download File

0 Comments

10th Biology:HEREDITY AND EVOLUTION SOLVED

10th Biology Guess Paper Solved for CBSE[SA-II]

6th Science practice questions Air around Us

Class 6th Chapter-(Garbage In, Garbage Out ,Waste) [CBSE Assignments]

8th Pollution of Air and Water [Science Solution]

8th Conservation of Plants and Animals[Questions with Solution]

ASSIGNMENT- CLASS 8-BIOLOGY- REPRODUCTION IN ANIMALS

Three Dimensional Figures for class 8th Maths

8th parallelogram worksheet and Assignments

Blog Posts Categories

Join Us For Update

Author

Blog Archives

Comment & Submit Papers

Blog Posts Categories

Join Us For Update

Author

Blog Archives

﻿﻿Comment & Submit Papers﻿﻿

Comment & Submit Papers