Consider the following statements:
1. The aperture of the pupil of a human eye can be changed with the help of the ciliary muscles.
2. The curvature of human eye cannot be changed, because the lens of a human eye is fixed.
Which of the statements given above is/are correct?
ANSWER: (D)
The Pupil
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With reference to the uses of ‘concave mirrors’, read the following statements carefully:
1. They are commonly used in vehicles headlights to get powerful parallel beams of light.
2. They are often used as shaving mirrors to see a larger image of the face.
3. They are fitted on the sides of the vehicle to have a wider field of view.
4. Large concave mirrors are used to concentrate sunlight to produce heat in solar furnaces.
Which of the statements given above is/are correct?
The immune system is a complex network of cells known as immune cells that contains lymphocytes. In this context, consider the following statements:
1. Lymphocytes are red blood cells and one of the body's main types of immune cells.
2. Lymphocytes are made in the bone marrow and found in the blood and lymph tissue.
Which of the statements given above is/are correct?
Water vapour present in the atmosphere is formed due to which of the following factors?
1. Heating of water bodies.
2. Activities of living organisms.
3. Weathering of rocks.
4. Photosynthesis.
Select the correct answer using the code given below:
Read the following statements carefully in the context of ‘particulate pollutants’?
1. Smoke particulates consist of gaseous or mixture of gaseous and liquid particles formed during combustion of organic matter.
2. Dust is composed of fine solid particles produced during crushing, grinding and attribution of solid materials.
3. Mists are produced by particles of spray liquids and by condensation of vapours in air.
4. Fumes are generally obtained by the condensation of vapours during sublimation, and boiling.
Which of the statements given above are correct?
Consider the following statements:
1. Tendons are type of connecting tissue that connect muscles to bones.
2. Nerve impulses are transmitted with the help of tendons throughout our body.
Which of the statement(s) given above is/are correct?
Which of the following statement(s) about Acquired Immuno Deficiency Syndrome (AIDS) is/are correct?
1. AIDS is a congenital disease caused by a retrovirus known as Human Immuno deficiency Virus (HIV).
2. AIDS is characterised by a progressive decrease in the number of T-lymphocytes in the body of the infected person.
Select the correct answer using the code given below.
Which of the following phenomena are caused due to ‘atmospheric refraction’?
1. Flickering of objects seen through a turbulent stream of hot air rising above a fire.
2. The reddening of the sun at sunrise and the sunset.
3. The apparent flattening of the Sun’s disc at sunrise and sunset.
4. The Sun is visible to us about 2 minutes before the actual sunrise, and about 2 minutes after the actual sunset.
Select the correct answer using the code given below.
Some countries now use alcohol as an additive in petrol. In context of this, consider the following statements:
1. Addition of alcohol increases the burning efficiency of petrol and reduces knocking.
2. Petrol added with small quantities of alcohol becomes more stable and doesn’t become too hot in warm areas or too cold in freezing temperatures.
3. Alcohol is a cleaner fuel which gives rise to only carbon dioxide and water on burning in sufficient oxygen.
Which of the statements given above is the correct reason for using alcohol as an additive in petrol?
Read the following statements carefully and select the correct answer from codes given below:
1. Working of electric motors involves the electric effect of electric current.
2. Working of electric generators involves the magnetic effect of moving magnets.
Which of the statement(s) given above is/are correct?
The most common nutrients causing eutrophication are: