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Observe the following figures. i) Identify the stages a to d in Fig. during the development of the human baby. ii) Arrange the stages in the correct sequence of development. iii) Explain the development that takes place in any one stage.

(i) (a) Embedding of the embryo in the uterus. (b) Fertilisation. (c) Zygote formation and development of an embryo from the zygote. (d)... View Article

Match the names of scientists given in Column A with the discovery made by them given in Column B. Column A – Column B (a) Louis Pasteur – (i) Penicillin (b) Robert Koch – (ii) anthrax bacterium (c) Edward Jenner – (iii) Fermentation (d) Alexander Fleming – (iv) small pox vaccine

The correct matching for the given question is as follows- (a) Louis Pasteur - (iii) Fermentation (b) Robert Koch - (ii) Anthrax bacterium (c)... View Article

Amoeba is a _____ celled organism. It reproduces by _ reproduction. The process of reproduction begins by the division of its _ into two. This is followed by the division of its _ into two. This type of reproduction is called _______ fission. Fill up the blanks with the terms: (body. asexual, binary, single, nucleus)

Amoeba is a single celled organism. It reproduces by asexual reproduction. The process of reproduction begins by the division of... View Article

Given below are events that lead to pregnancy and development of the embryo. i) Fertilization of egg ii) Maturation of egg iii) Release of egg iv) Embedding of the embryo in the thickened uterine wall. Which of the following options gives the correct order of sequence in which they occur? (a) i, ii, iii, iv, (b) ii, i, iii, iv (c) i, iv, ii, iii (d) ii, iii, i, iv

d) ii, iii, i, iv The sequence of events is as follows: 1. Maturation of egg after puberty. 2. Release of the egg cell. 3. Fertilization of the... View Article

Read the statements given below. (i) Seeds require moisture for germination. (ii) Plants can absorb nutrients mostly in dissolved form. (iii) Irrigation protects crops from both frost and hot air currents. (iv) Irrigation improves soil texture. Choose the combination of statements which indicate the need to irrigate crops. (a) i and ii (b) i, ii, iii (c) i, ii, iii, iv (d) i and iii

(a) i and ii Irrigation is necessary because water is required for germination of seeds. It is the supply of water to crops at regular intervals,... View Article

Which of the following statements are true about the brain? (i) The main thinking part of the brain is the hindbrain (ii) Centres of hearing, smell, memory, sight etc are located in forebrain. (iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hindbrain (iv) Cerebellum does not control the posture and balance of the body (a) (i) and (ii) (b) (i), (ii) and (iii) (c) (ii) and (iii) (d) (iii) and (iv)

c) (ii) and (iii) On average, an adult brain weighs between 1.0 kg – 1.5 kg. It is mainly composed of neurons – the fundamental... View Article

Following are a few organisms (a) lichen (b) mosses (c) mango tree (d) cactus Which among the above can grow on stones; and also help in the formation of soil? Write the mode of their action for making soil.

Lichens and mosses grow on rocks. Lichens and mosses release chemical substances which break down the stones resulting in the formation of soil.... View Article

Differentiate the following activities on the basis of voluntary (V) or involuntary (I V) muscles. (a) Jumping of frog (b) Pumping of the heart (c) Writing with hand (d) Movement of chocolate in your intestine

Voluntary : a) Jumping of frog c) Writing with hand Involuntary : b) Pumping of the heart d) Movement of chocolate in your intestine When an... View Article

Name the hormone which would be released during the following situations: (a) a frightened person. (b) growth of a child to an adult. (c) development of caterpillar to moth. (d) development of tadpole to frog.

a. Adrenaline. It is secreted by adrenal gland during emergency situations. It helps us to face the situation or flight away from it. It is... View Article

Identify the correct statement about cells. (a) All the cells have nucleus. (b) Cells of an organ have similar structure. (c) Cells of tissue have a similar structure. (d) The shape of all types of cells is round.

c) Cells of a tissue have similar structure. Only eukaryotic cells have well-defined nucleus, hence option a) is wrong. Cells of an organ... View Article

Paddy is a major cereal crop in our country. (a) In which season is paddy cultivated? (b) Discuss the method of sowing. (c) What measures must be taken to prevent spoilage and insect attack of harvested grains?

a) Paddy is cultivated in rainy season as it is a Kharif crop. b) For sowing paddy seeds are first grown in the nursery then the seedlings are... View Article

Fill in the blanks. (a) A place where animals are protected in their natural habitat is called _____ . (b) Species found only in a particular area is known as _ . (c) Migratory birds fly to faraway places because of ________ changes.

a) A place where animals are protected in their natural habitat is called wildlife sanctuary. A wildlife sanctuary is an area where animal... View Article

A student heats a beaker containing ice and water. He measures the temperature of the content of the beaker as a function of time. Which of the following (Fig.) would correctly represent the result? Justify your choice.

d) At the start of the experiment temperature of the mixture would be zero as water and ice will be in equilibrium. When students start heating... View Article

Observe the set up given in Fig. and answer the following questions. (a) What happens to the sugar solution in A? (b) Which gas is released in A? (c) What changes will you observe in B when the released gas passes through it?

a) Yeast ferments sugar to convert it to alcohol and carbon dioxide is released. b) Carbon dioxide c) CO2 Converts limewater milky.... View Article

Lack of oxygen in muscles often leads to cramps among cricketers. This results due to (a) conversion of pyruvate to ethanol (b) conversion of pyruvate to glucose (c) non-conversion of glucose to pyruvate (d) conversion of pyruvate to lactic acid

d) Conversion of pyruvate to lactic acid Lack of oxygen in muscles leads to cramps, fatigue sometimes swelling as the body sometimes lacks... View Article

Observe the Fig. and answer the following questions. (a) Name the microorganism and the group to which it belongs. (b) Name the food item on which the organism grows. (c) Does it grow well in dry or in moist conditions? (d) Is it safe to eat infected bread?

a) The image is of bread mould. It is a fungus b) It grows on moist and stale bread c) It grows well in moist conditions d) No, it is not safe... View Article

What are the consequences of the following conditions? (a) A cell containing higher water concentration than the surrounding medium (b) A cell having low water concentration than the surrounding medium. (c) A cell having equal water concentration to its surrounding medium.

(a) When a cell possess higher water concentration than the surrounding medium then exosmosis occurs In the cell due to the difference in water... View Article

Choose the correct statement about inflammable substances from the following. They have: (a) low ignition temperature and cannot catch fire easily. (b) high ignition temperature and can catch fire easily. (c) low ignition temperature and can catch fire easily. (d) high ignition temperature and cannot catch fire easily.

(c) low ignition temperature and can catch fire easily. The inflammable substances are the substances that easily catch fire. They are... View Article

After observing Fig. answer the following. a) Read the following statements and label them in the figure: i) The part which produces female gametes. ii) The part where the development of the baby takes place. iii) The part through which the developing embryo passes to reach the uterus. b) Explain the future development of the embryo that would take place after it gets embedded in the uterus.

Solution: Ovary Uterus Oviduct The developing embryo gets embedded in the wall of the uterus for further development. The embryo continues to... View Article

Figure shows the two crop fields [Plots A and B] have been treated by manures and chemical fertilizers respectively, keeping other environmental factors same. Observe the graph and answer the following questions. (i) Why does plot B show sudden increase and then gradual decrease in yield? (ii) Why is the highest peak in plot A graph slightly delayed? (iii) What is the reason for the different pattern of the two graphs?

i) With addition of chemical fertilizer there is sudden increase in yield due to release of nutrients N,P,K etc in high quantity. The gradual... View Article

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