Biology Questions and Answers

Earthworms don't have red blood because they exchange gas with their skins. The color of blood is red due to the presence of hemoglobin in the red blood cell that helps transport oxygen.

Root hair cells are adapted to absorb the water out of the soil by osmosis– they have a large surface area, thin walls, and are close to the xylem cells used to transport water up the plant. Minerals such as nitrate ions cannot be absorbed by osmosis (which is the movement of water only) or diffusion (because the minerals are in very low concentration). The root hair cells have carrier molecules on their surface that pick up the minerals and move them into the cell against the concentration gradient. This requires energy, and is called active transport.

A hygrometer is a weather instrument used to measure the amount of humidity in the atmosphere. There are two main types of hygrometers: a dry and wet bulb psychrometer and a mechanical hygrometer.

Humidity is the measure of the amount of moisture in the air. A psychrometer is an example of a hygrometer.

Hens do not have mammary glands.

Insulin and glucagon are hormones secreted by islet cells within the pancreas. They are both secreted in response to blood sugar levels.

Insulin helps control blood glucose levels.