Q151. The primary role of chlorophyll in photosynthesis is to:
Basics of Everyday Science: RAS Prelims MCQs
200 RAS Prelims MCQs on the basics of everyday science test the scientific method, the laws of motion, chemical bonding and the cell theory. The questions use daily-life examples, such as the recoil of a gun and the orbit of a satellite, and the explanations give the principle behind each example so that you can reason out similar questions.
Practice questions based on the RPSC RAS Prelims syllabus. They follow the exam pattern but are not past-paper questions.
Showing 151–160 of 200 questions
Q152. Match the processes in List I with their site of occurrence in the cell in List II.
| Process/Stage | Site of occurrence in the cell |
|---|---|
| A. Glycolysis | i. Mitochondrial matrix |
| B. Krebs Cycle (Citric Acid Cycle) | ii. Cytoplasm |
| C. Light reaction of photosynthesis | iii. Stroma of chloroplast |
| D. Dark reaction (Calvin cycle) | iv. Thylakoids of chloroplast |
Explanation
Glycolysis occurs in the cytoplasm, while the Krebs cycle takes place in the mitochondrial matrix. In photosynthesis, the light-dependent reactions occur within the thylakoid membranes of the chloroplast, where light is captured. The light-independent dark reactions, or the Calvin cycle, take place in the surrounding stroma. These specific locations ensure that the necessary enzymes and substrates are concentrated for metabolic activity.
Q153. During the light-dependent reactions of photosynthesis, oxygen gas is released as a byproduct of:
Explanation
During the initial light-dependent stage of photosynthesis, light energy is used to split water molecules into hydrogen ions, electrons, and oxygen gas. This process is known as photolysis. The electrons and hydrogen ions are utilized in the electron transport chain to generate ATP and NADPH, while the oxygen gas is released into the atmosphere as a vital byproduct of the reaction.
Q154. Tiny pores on the surface of plant leaves that facilitate gas exchange are called:
Explanation
Stomata are microscopic pores located primarily on the undersides of plant leaves. They are surrounded by specialized guard cells that regulate their opening and closing. These openings are essential for gas exchange, allowing carbon dioxide to enter for photosynthesis and oxygen to exit. However, they also facilitate transpiration, the loss of water vapor from the plant into the surrounding environment.
Q155. Aerobic respiration differs from anaerobic respiration in that it:
Explanation
Aerobic respiration is a high-efficiency metabolic process that completely breaks down glucose to produce energy, and it strictly requires the presence of oxygen. In contrast, anaerobic respiration occurs in the absence of oxygen and is much less efficient, producing far less ATP per glucose molecule. Aerobic respiration results in carbon dioxide and water, while anaerobic processes produce lactic acid or ethanol.
Q156. The universal energy currency molecule generated during cellular respiration is:
Explanation
Adenosine Triphosphate, commonly known as ATP, is the universal energy currency for all living cells. It stores chemical energy in high-energy phosphate bonds that can be easily broken to power various cellular processes, including muscle contraction, active transport, and chemical synthesis. ATP is continuously generated during cellular respiration and consumed during metabolic work, maintaining the life-sustaining activities of the organism.
Q157. Which of the following processes is common to both aerobic and anaerobic respiration?
Explanation
Glycolysis is the initial stage of glucose metabolism and is common to both aerobic and anaerobic respiration. This metabolic pathway occurs in the cytoplasm and does not require oxygen to function. It involves the breakdown of one glucose molecule into two molecules of pyruvate, producing a small net gain of ATP and providing the necessary precursors for subsequent metabolic stages.
Q158. Consider the following factors affecting the rate of photosynthesis:
I. Light intensity
II. Carbon dioxide concentration
III. Temperature
IV. Availability of water
V. Atmospheric nitrogen concentration
Which of the above statement(s) identify the primary limiting factors for photosynthesis?
I. Light intensity
II. Carbon dioxide concentration
III. Temperature
IV. Availability of water
V. Atmospheric nitrogen concentration
Which of the above statement(s) identify the primary limiting factors for photosynthesis?
Explanation
Several environmental factors directly influence the rate of photosynthesis. Light intensity provides the energy, carbon dioxide concentration supplies the raw material, and temperature affects the activity of the enzymes involved. Water availability is also crucial, as it is a reactant and maintains plant health. Atmospheric nitrogen, while abundant, is not a direct reactant or primary limiting factor for photosynthesis.
Q159. Muscle cramps in human bodies during heavy exercise are caused by the accumulation of:
Explanation
During intense physical exercise, the demand for energy may exceed the oxygen supply to the muscles. This leads to anaerobic respiration, where glucose is partially broken down into lactic acid instead of being completely oxidized. The accumulation of lactic acid in the muscle tissues causes a drop in pH, leading to fatigue and the painful involuntary contractions commonly known as muscle cramps.
Q160. The Respiratory Quotient (R.Q.) is defined as the ratio of:
Explanation
The Respiratory Quotient, or R.Q., is a dimensionless number used in biological calculations to determine the type of fuel being metabolized by an organism. It is calculated as the ratio of the volume of carbon dioxide evolved to the volume of oxygen consumed during respiration. The R.Q. value varies depending on whether carbohydrates, fats, or proteins are being used for energy.Answer key for these questions
| Q | Correct answer |
|---|---|
| 151 | (d) Absorb light energy |
| 152 | (a) A-ii, B-i, C-iv, D-iii |
| 153 | (c) The photolysis of water molecules |
| 154 | (a) Stomata |
| 155 | (d) Strictly requires the presence of oxygen |
| 156 | (b) ATP (Adenosine Triphosphate) |
| 157 | (c) Glycolysis |
| 158 | (a) I, II, III and IV |
| 159 | (a) Lactic acid |
| 160 | (b) Carbon dioxide evolved to oxygen consumed |
Key facts from Basics of Everyday Science
- Inductive reasoning draws a general conclusion from specific observations; a control variable is kept constant in an experiment; communicating the results is the last step of the scientific method.
- Newton’s second law relates force, mass and acceleration; the recoil of a gun illustrates the third law.
- Momentum is the product of mass and velocity; impulse is equal to the change in momentum.
- A satellite in uniform circular orbit is held by the centripetal force provided by gravity.
- Water (H₂O) and N₂ show covalent bonding; sodium chloride, MgO and CaF₂ are ionic.
- The classical cell theory does not say that all cells have a true nucleus.
Frequently asked questions
How many RAS Prelims practice MCQs are there on Basics of Everyday Science?
This page has 200 practice MCQs on Basics of Everyday Science (Science and Technology). Each has the correct answer, and most have an explanation.
What is the product of mass and velocity called?
Momentum. Newton’s second law says that the rate of change of momentum is equal to the force applied, and impulse is equal to the change in momentum of a body.
Which law explains the recoil of a gun?
Newton’s third law of motion. The gun pushes the bullet forward, and the bullet pushes the gun back with an equal and opposite force, which is felt as recoil.
What holds a satellite in a circular orbit?
The centripetal force provided by gravity. The Earth’s pull keeps changing the direction of the satellite’s velocity so that it moves in a circle and does not fly off in a straight line.