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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... 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... 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 Explanation Lack of oxygen in muscles leads to cramps, fatigue sometimes swelling as... 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)... 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... 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... 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... 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... View Article

Read the following pairs of examples of organisms: (a) moss and sponge (b) yeast and Amoeba (c) bacteria and a blue-green alga (d) penicillium and Spirogyra The pair that belongs to the group prokaryotes is_____

(c) bacteria and a blue-green alga Blue-Green Algae are a type of photosynthetic bacteria consisting either of single cells or... View Article

Weeds affect the crop plants by (a) killing of plants in field before they grow (b) dominating the plants to grow c) competing for various resources of crops (plants) causing low availability of nutrients (d) all of the above

c) Competing for various resources of crops causing low availability of nutrients Explanation Weeds are defined as the unwanted plants... View Article

Choose the wrong statement (a) High blood pressure is caused by excessive weight and lack of exercise. (b) Cancers can be caused by genetic abnormalities (c) Peptic ulcers are caused by eating acidic food (d) Acne is not caused by staphylococci

c) Peptic ulcers are caused by eating acidic food. Explanation Peptic ulcer is caused by bacterium Helicobacter pylori.Peptic ulcers are... View Article

We eat food composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water. After digestion, these are absorbed in the form of glucose, amino acids, fatty acids, glycerol etc. What mechanisms are involved in the absorption of digested food and water?

Diffusion is a process in which the molecules intermingle due to their kinetic energy and movement of molecules is from... View Article

Suggest a suitable word for each of the following statements. (a) Chemicals added to food to prevent the growth of microorganisms. (b) Nitrogen-fixing microorganism present in the root nodules of legumes. (c) The agent spreads pathogens from one place to another. (d) Chemicals which kill or stop the growth of pathogens.

(a) Preservatives are the chemicals added in food. They prevent microbial infection without altering the taste or appearance.(b) Rhizobium are... View Article

John and Radha were classmates since childhood. When Radha became eleven years old, she developed a little swelling on her neck. She visited the doctor who started medication for her. After a few years, John also developed a slight protrusion on his throat. He got worried and went to the doctor. But, the doctor assured him that it was a normal feature in boys while they are growing up. Can you think of any reasons for the difference in diagnoses?

The swelling on the neck of Radha may have been because of goiter, a condition of the thyroid gland during... View Article

If you are provided with some vegetables to cook, you generally add salt to the vegetables during the cooking process. After adding salt, vegetables release water. What mechanism is responsible for this?

Exosmosis is the process of movement of water molecules from inside to the outside of the cell, where the solution... View Article

Anu wants to boil water quickly in a test tube. On observing the different zones of the flame, she is not able to decide which zone of the flame will be best for boiling water quickly. Help her in this activity.

Anu should boil the water in the hottest zone of the flame, which is non-luminous zone or the outermost zone... View Article

The property to flow is unique to fluids. Which one of the following statements is correct? (a) Only gases behave like fluids (b) Gases and solids behave like fluids (c) Gases and liquids behave like fluids (d) Only liquids are fluids

(c) Gases and liquids behave like fluids Gases and liquids behave like fluids. Both gases and liquids tend to flow... View Article

It is believed that the height of a child depends upon the genes inherited from parents. However, it is often seen that tall parents may have short children and vice-versa. Are there factors other than genes, that can cause these variations?

Yes, though the height of a child depends upon genes inherited from a parent there are various factors which affect... View Article

Generally, metallic oxides are basic and non-metallic oxides are acidic in nature. The solution of which of the following oxides in water will change the colour of blue litmus to red? (a) Sulphur dioxide (b) Magnesium oxide (c) Iron oxide (d) Copper oxide

Sulphur dioxide The oxides of a metal are basic in nature or in other words they react with acids to... View Article

Find out incorrect sentence (a) Parenchymatous tissues have intercellular spaces (b) Collenchymatous tissues are irregularly thickened at corners (c) Apical and intercalary meristems are permanent tissues (d) Meristematic tissues, in its early stage, lack vacuoles

c) Apical and intercalary meristems are permanent tissues Apical and intercalary meristems are not themselves permanent tissue instead they differentiate to... View Article

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