Explanation

The age of a tree is determined by counting its growth rings (annual rings) in the trunk.

Each ring typically represents one year of growth.

Explanation

Chlorella is a unicellular green alga, meaning the entire organism consists of a single cell.

Bacteria are also unicellular but are prokaryotic, while Chlorella is eukaryotic.

Viruses are not made of cells at all.

Explanation

The process of detecting a change and signaling the effector's response in a control system is called a feedback mechanism.

This mechanism involves a receptor detecting a change, a control center (integrator) processing the information, and an effector carrying out the necessary response to maintain or restore a desired state. 

Explanation

A hypothesis is a tentative explanation for an observation or a scientific problem.

It is testable through experiments and forms the basis for further investigation.

Explanation

Heterocysts are specialized nitrogen-fixing cells found in some cyanobacteria (e.g., Anabaena).

They provide an anaerobic environment necessary for the enzyme nitrogenase to fix atmospheric nitrogen.

Explanation

The MN blood group system shows co-dominance, where both M and N alleles are equally expressed in the phenotype.

Individuals can have M, N, or MN blood types, with MN expressing both traits simultaneously.

Explanation

The sodium-potassium pump (Na⁺/K⁺-ATPase) actively transports 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell for each cycle,

For maintaining the electrochemical gradient

Explanation

Nails, feathers, hair, and horns are made up of proteins.

These structures primarily consist of keratin.

Keratin is a type of protein that provides strength and durability.

Explanation

Vitamin B deficiency can cause diseases such as:

• beriberi
• pellagra 
• anemia

Vitamin B12 deficiency anemia happens when your body does not have enough healthy red blood cells

Explanation

• The nucleus is responsible for cell division because it contains chromosomes, which are made up of DNA and proteins.
• Chromosomes carry the genetic information necessary for cell division, growth, and function.