Sunday, March 15, 2015

Science Worksheet

1. ‘The sex of a newborn child is a matter of chance and none of the parents may be
considered responsible for it.’ Justify this statement with the help of flow chart showing
determination of sex of a newborn. [3]
2. Tabulate two distinguishing features between acquired traits and inherited traits with
one example of each. [3]
3. Write two examples each of sexually transmitted diseases caused by (i) virus, (ii)
bacteria. Explain how the transmission of such diseases can be prevented?
4. [3]
(a) Explain the process of regeneration in Planaria.
(b) How is regeneration different from reproduction?
5. An object of height 5 cm is placed perpendicular to the principal axis of a concave lens
of focal length 10 cm. Use lens formula to determine the position, size and nature of the
image, if the distance of the object from the lens is 20 cm.(h=1.66cm)
6. [5]
(a) Write the function of placenta in females.
(b) List four ways of preventing pregnancy. State two advantages of using such
preventive methods.
7. State Snell's law of refraction of light. Write an expression to relate refractive index of a
medium with speed to light in vacuum.
8. In the figure, the parts marked A, B and C are sequentially:
9. A drop of colourless liquid is poured over blue litmus paper and it turns to red. The
colourless liquid is
(a) Potassium hydroxide solution(b) Sodium chloride solution(c) Pure water(d) Dilute hydrochloric acid
10. A student heated ferrous sulphate crystals in a test tube. He would observe that [1]
(a) The crystals start melting(b) The crystals evaporate(c) A very pungent gas is given out(d) The crystals catch fire
11. The action of water on quicklime is classified as a combination reaction because.
12. Aradhita added zinc granules in an iron sulphate solution and made a few observations.
Identify the incorrect observation.
i. Pale green solution becomes colourless             ii. Black deposit seen on zinc granules
iii. Red deposit seen on zinc granules                     iv. Colourless solution becomes pale green
 
13.  State with reason any two possible consequences of elimination of decomposers from the Earth.



14. . How is charcoal obtained from wood? Why charcoal is considered a better fuel than wood?
15. Describe how hydro-energy can convert into electrical energy. Write any two limitations of hydro – energy?
16.  List any four advantages of water harvesting
17.
18.  How will an organism be benefited if it reproduces through spores?
19.  Why is vegetative propagation practiced for growing some types of plants?
  20. : Define Ecology
21: Define Ecosystem. Is garden an example of Ecosystem?
22. A beam of light is allowed to pass through two beakers A and B, containing a true
solution and a colloidal solution respectively. What do you observe ? Name the phenomenon
responsible for your observation.
23. What are Rods and Cones ?
24.  If the earth had no atmosphere, what change would be obsered in the length of day ?
Given reason.
25.  What is cataract ? How do we rectify the same?
26.  Which part of the eye can be donated after death ?
27.  Why do we observe random wavering or flicking of the objects near a fire or on a
very hot day ?
28 The near point of a hypermetropic person is 75 cm from the eye. What is the power
of the lens required to enable him to read clearly a book held at 25 cm from the eye ?
29. Explain why ?
(a) Myopic person prefer to remove his spectacles while reading a book.
(b) A hypermetropic person prefer to remove the spectacles while looking at the sky.
30 (a) How do we see colours?
(b) Which cells on the retina responded to intensity of light ?
(c) Explain the basic role of these cells.
31. Explain the role played by
(i) Ciliary muscles, (ii) Aqueous humour.
32 You are given four lenses namely, bi focal
lens, convex lens, concave lens and cylindrical lens. Which lens would you prefer to correct the myopia, hypermetropia, astigmatism and presbyopia respectively?

33.  A person needs a lens of power – 5.5 dioptres for correcting his distant vision. For
correcting his near vision he needs a lens of power + 1.5 dioptre.What is the focal length of
the lens required for correcting
(i) distant vision (ii) near vision?
34.  A boy uses lens of focal length + 40 cm in his spectacles. Name the defect of vision he
is suffering from.
35: Define biological magnification.
36. What will happen if we kill all the organisms in one trophic level?
37. What are the problems caused by the nonbiodegradable wastes that we generate?
38. Why is the damage to the ozone layer a cause for concern?What steps are being taken
to limit this damage?
39. What is Mendel’s factor better known as?
40.  Expand RNA and DNA     41. Give two functions of chromosomes 42. What do you mean by autosomes
43.“Theory of Natural Selection” was proposed by which scientist? Explain this theory briefly
Answers.
10.  Very pungent gas is given out.
When ferrous sulphate crystals are heated in a test tube, pungent smell of burning
sulphur is obtained due to formation of sulphur dioxide gas.
12.  A black not red deposit is seen on the zinc granules.
   Pale green solution of iron sulphate turns colorless.
14. Solution:
When wood is burnt in a limited supply of oxygen, water and volatile materials present in it get removed and charcoal is left behind as the residue.
 Charcoal is considered a better fuel wood because:
  i)  Charcoal has higher calorific value than wood.             ii) It burns smoothly and produces less smoke.
iii) It leaves fewer residues.        iv) It is a more compact fuel than wood and has higher percentage of combustible matter in it.            v) It has lower ignition temperature than wood.
16.  Four advantages of water harvesting can be listed as
Production of energy in large quantities,                               Increases the aquatic biomass,  Increases soil fertility
Water table levels in underground is well maintained
18. The spores are covered by thick wall that protects them from unfavorable conditions like lack of
food, water or high temperature. But as the conditions become favorable these spores can grow to
produce new plant.
20. Ecology is a scientific study of the interactions between organisms and the environment.
21. An environment comprises of all living (biotic) and nonliving
(abiotic) things that occur naturally on the Earth or any of its region. All these living organisms interact with each other and their growth, reproduction and other activities are affected by the abiotic components of ecosystem.
27. The air above the fire or air above ground on hot day expands. This causes its refractive index to
change. The light passing through it is refracted. As the physical condition of air changes continues , the
refraction is not constant . This gives a wavering effect to objects near the fire or on a hot day.
28. 2.67D
33. -18.18cm,66.6cm
35 It means accumulation of poisonous materials in successive trophic levels in a food chain.
38. Steps being taken to limit this damage are (i) To protect ozone layer, the United Nations environment program forged an agreement to freeze  CFC production at 1986 levels.           (ii) Chlorofluoro carbons are now being replaced by hydrofluorocarbons
which do not damage the ozone layer.
41. They contain genes which are the information carriers and a link between parents and zygote.
(ii) They help in regulating the metabolism, cell differentiation and proteins synthesis
42. Autosomes are the chromosomes which are associated with the functioning of the cells and determination of characters and traits of the individual. There are22 pairs of autosomal chromosomes in human beings.


Find Least Common Multiple (LCM). 1) 5 and 15 = ...