LIFE SCIENCE

OBJECTIVE LIFE SCIENCE

BIOCHEMISTRY

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Water striders can walk across the surface of calm water. Their feet push the surface of the water down slightly, but they do not break the surface. Why?
A
The insects are light enough so they do not break the hydrogen bonds holding the water molecules together (cohesion)
B
The insects actually use their wings to hover slightly above the water’s surface and they only skim it with their feet.
C
The insect’s feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water’s surface.
D
The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next
Explanation: 

Detailed explanation-1: -Water striders can walk across the surface of calm water. Their feet push the surface of the water down slightly, but they do not break the surface. Why? The insects actually use their wings to hover slightly above the water’s surface and they only skim it with their feet.

Detailed explanation-2: -Water striders use the high surface tension of water and long, hydrophobic legs to help them stay above water. Water striders use this surface tension to their advantage through their highly adapted legs and distributed weight.

Detailed explanation-3: -They can suspend themselves and live their lives on the surface of water because their bodies are covered with small hairs that trap air, providing them with sufficient buoyancy to make the surface tension of water stronger than the force of gravity pulling down on their small bodies.

Detailed explanation-4: -Water striders are small insects that are adapted for life on top of still water, using surface tension to their advantage so they can “walk on water.”

Detailed explanation-5: -Because of hydrogen bonding, water can actually support objects that are more dense than it is. Water molecules stick to one another on the surface, which prevents the objects resting on the surface from sinking. This is why water striders and other insects can “walk” on water!

There is 1 question to complete.