SOLVED PAPER 2021 (CDS) (I) (General Awareness)

Total Questions: 120

91. Cell wall is not present in cells of

Correct Answer: (d) Humans
Solution:A cell wall is a dead, rigid and protective structural layer surrounding some types of cells, just outside the cell membrane. Its major function is to act as pressure vessels, preventing over-expansion of the cell when water enters and protects cell from outer shock and invasion of other unwanted materials. Cell walls are absent in animals and humans, but are present in most other eukaryotes including algae, fungi and plants and in most prokaryotes.

92. A child receives a tall beautiful plant as a birthday gift from his father with a quiz. The father. asked her how she would verify whether this tall plant was the progeny of both the tall parents or one tall and one short parent plant. She could verify this through

Correct Answer: (b) self-pollination
Solution:Self-pollination is a form of pollination in which pollen from the same plant arrives at the stigma of a flower. There are two types of self-pollination: in autogamy, pollen is transferred to the stigma of the same flower; in geitonogamy, pollen is transferred from one of the flower to the stigma of another flower on the same flowering plant, or from microsporangium to ovule within a single gymnosperm. Due to self-pollination, if all new progenies are tall than the parents of that plant were both tall, but if there are few short plants in new progenies than one of the parent of that plant was short and other one was tall.

93. A student was doing an experiment on increasing the cell division among plants. She asked her supervisor to suggest the specific plant hormone for the same. Had you been her supervisor, which plant hormone would you suggest?

Correct Answer: (c) Cytokinin
Solution:Cytokinins (CK) are a class of plant hormones that promote cell division or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.

94. Which cell organelles have their own DNA and Ribosomes?

Correct Answer: (b) Mitochondria and Plastids
Solution:Mitochondria and Plastids like Chloroplast have their own DNA and 70 s ribosomes because of which they are able to synthesise some of their own proteins and replicate independent of the nucleus. Thus, known as semi-autonomous cell organelles.

95. Osmosis is the process of movement of water molecules from its

Correct Answer: (d) higher concentration to its lower concentration through a semi-permeable membrane.
Solution:Osmosis is a process by which the molecules of a solvent pass from a solution of low concentration to a solution of high concentration through a semi-permeable membrane.

96. Growing of two or more crops simultaneously on the same field in a definite pattern is known as

Correct Answer: (b) inter cropping
Solution:Intercropping is a multiple cropping practice that involves growing two or more crops in a definite pattern simultaneously on the same field.

97. When we heat lead nitrate [Pb (NO₃)₂] in a boiling tube, we observe the emission of brown fumes. Which one of the following is the brown gas ?

Correct Answer: (d) NO₂
Solution:When lead nitrate [Pb (NO₃)₂] is heated strongly it breaks down to form simpler substances like lead monoxide (PbO), nitrogen dioxide (NO₂) and oxygen (O₂). In this decomposition reaction the colourless compound lead nitrate forms a yellow compound lead monoxide and brown fumes of nitrogen dioxide gas are evolved.

98. Which one of the following substances do silver articles react with, that makes the silver articles black?

Correct Answer: (a) Sulphur
Solution:Silver articles, when exposed to air become black after sometime. This is because the silver metal reacts with sulphur present in the atmosphere and forms silver sulphide. Thus, a layer of silver sulphide is formed on the surface of silver articles, because of which they appear dull and black.

99. Which one of the following metals is kept immersed in Kerosene oil to protect it and to prevent accidental fire?

Correct Answer: (b) Sodium
Solution:Sodium is kept in kerosene because it is a highly reactive metal. If it is kept in an open container, it will react with oxygen and water vapor present in the atmosphere producing sodium oxides and sodium hydroxides respectively which is a highly exothermic reaction.

100. A solution contains 20g of solute in 180g of solvent. If the solvent is water, what is the concentration of the solution in terms of mass by mass percentage?

Correct Answer: (c) 10%
Solution: