All Free Biology MCQs with Answers

4181. All are properties of water except:

• A. Universal solvent
• B. Polar nature
• C. Hydrogen bonding
• D. Becomes denser when it freezes.

Explanation: The statement in option (d) is false and not a property of water. Water actually becomes less dense when it freezes. This occurs because the hydrogen bonds between water molecules form a crystalline structure in ice that is less compact than in liquid water, causing ice to float.

4182. _ is the heat required to convert a gram of water into vapours at its boiling point.

• A. Heat of vapourization
• B. Specific heat capacity
• C. Heat of ionization
• D. Polarity of water

Explanation: The heat of vaporization is the amount of heat energy required to convert a unit mass of a substance (in this case, water) from its liquid phase to its vapor phase at its boiling point. For water, the heat of vaporization is approximately 2250 kJ/kg or 540 cal/g.

4183. The attraction among water molecules which hold water together is called:

• A. Tension.
• B. Cohesion.
• C. Adhesion.
• D. Ambibition.

Explanation: Cohesion: Hydrogen bonds make water sticky. Water has an amazing ability to adhere (stick) to itself and to other substances. The property of cohesion describes the ability of water molecules to be attracted to other water molecules, which allows water to be a "sticky" liquid.

4184. The property of water which helps to maintain the integrity of the lipid bilayer is

• A. High specific heat capacity
• B. Hydrogen bonding
• C. Cohesion and tension
• D. Hydrophobic exclusion

Explanation: Hydrophobic exclusion cause water molecules to be repelled by the hydrophobic tails of phospholipids, causing them to cluster around the hydrophilic heads. This exclusion creates an environment where the hydrophobic tails are shielded from water, promoting the structural integrity of the lipid bilayer by preventing water from penetrating and disrupting its structure.

4185. Which one of the following is hypertonic solution to cells present in it?

• A. A
• B. B
• C. C
• D. None of these

Explanation: Option A is the hypertonic solution, as it causes the cells to shrink due to the movement of water out of the cell towards the higher solute concentration. Option B is the isotonic solution, and option C is the hypotonic solution as it causes the cells to fill with water due to the movement of water towards the lower solute concentration.

4186. The human body maintains all of its cells' internal concentration _ to internal body fluid.

• A. Isotonic
• B. Hypotonic
• C. Hypertonic
• D. Hyposmotic
• E. Hyperosmotic

Explanation: The human body maintains an isotonic environment, which means that the concentration of solutes is equal inside and outside of the cells. This helps to maintain a stable internal environment and prevent damage to cells from osmotic imbalances.

4187. Name the human tissues that contain about 85% water:

• A. Muscle cells
• B. Bone cells
• C. Brain cells
• D. None of the above

Explanation: The correct answer is brain cells. Brain cells, or neurons, have a high water content of approximately 85%, which is vital for their role in transmitting signals throughout the nervous system. Muscle cells also contain a significant amount of water, around 75%, but less than brain cells. Bone cells have a much lower water content, around 20%, due to their dense mineral composition. Therefore, the only tissue from the options provided that matches the high water content requirement is brain cells.

4188. The amount of heat energy required to raise the temperature of one gram of water by 1°C :

• A. Heat of neutralization of water
• B. Heat of condensation of water
• C. Heat of vaporization of water
• D. Specific heat of water

Explanation: The specific heat of water is a measure of the amount of heat energy needed to raise the temperature of one gram of water by 1°C. Water has a high specific heat compared to many substances, allowing it to absorb and retain heat effectively. This property plays a crucial role in regulating environmental and biological temperatures. Therefore, the correct answer is the specific heat of water. The other options refer to different types of heat energy changes that are not related to simply raising the temperature of water by 1°C.

4189. If water has a high latent heat of vaporization, how could this property of water be helpful to plants and animals?

• A. With the release of large amount of water, a small amount of heat loss can take place.
• B. With the release of small amount of water vapours, a great amount of heat loss can take place.
• C. It will keep their temperature very high.
• D. No cooling effect, with the release of even a large amount of water vapours.

Explanation: As per the formula Q=mL, since water has a high latent heat of vaporization (L), for a small mass or amount of water (m), a large amount of energy (Q) will be released which results in a large amount of heat loss, enabling the organism to remain cool via sweating (animals) or transpiration (plants). Option A describes this effect but in reverse, option C states the opposite effect as this process prevents their temperature from becoming too high, and option D is false as a cooling effect does indeed occur.

4190. Osmosis is the movement of

• A. Solute particles from higher concentration to lower concentration
• B. Solvent particles from higher water potential to lower water potential
• C. Solute particles from higher concentration to lower concentration through a semipermeable membrane
• D. Solvent particles from lower water potential to higher water potential

Explanation: Osmosis is the movement of water molecules from an area of high water potential to an area of low water potential through a semi-permeable membrane.