Explanation

The Watson-Crick model suggested that DNA replication is semi-conservative,

Meaning that each original DNA strand serves as a template to synthesize a new complementary strand,

This results in two DNA molecules, each containing one original strand and one newly synthesized strand. 

Explanation

The Central Nervous System (CNS) comprises the:

These two structures are the core of the nervous system, 

• The brain controls how we think, learn, move, and feel.
• The spinal cord carries messages back and forth between the brain and the nerves that run throughout the body..

Explanation

In the central nervous system, myelinated axons form the white matter.

Composition:

Primarily bundles of myelinated axons. 

Function:

To transmit signals rapidly and efficiently between different areas of the central nervous system. 

Color:

The lipid content of the myelin sheath gives the tissue a whitish appearance. 

Location:

Found in the deeper tissues of the brain (subcortical) and surrounds the centrally located gray matter of the spinal cord. 

Explanation

• The oesophagus is a muscular tube that connects the pharynx (throat) to the stomach.
• Its main function is to transport food from the pharynx to the stomach through peristalsis (wave-like muscle contractions).

Explanation

Human respiration releases carbon dioxide and water as waste products

After the cells use oxygen to break down food for energy.

While breathing (ventilation) involves taking in oxygen

And releasing carbon dioxide through the lungs,

Cellular respiration is the chemical process within the cells

That breaks down glucose using oxygen to produce energy, CO2, and water. 

Explanation

• The heart is the primary muscular organ
• Responsible for pumping blood
• Four chambers (two atria and two ventricles) that manage blood flow.
  It ensures that oxygen and nutrients are delivered to tissues and organs.

Last updated by NA on 23-April-2026

Explanation

Explanation

Explanation

72 beats per minute is a good heart rate.

Complete answer:

The resting person usually has a pulse rate between 70 (beats per minute) and 80 (beats per minute).

Your risk of dying from a heart attack is lower if your heart rate is below 80 beats per minute.

A normal resting heart rate ranges from 60 to 100 beats per minute.

Explanation

• The pupil is the small, circular opening in the center of the iris that appears as a black dot.
• It is the entrance point for light to enter the eye.
• It is responsible for controlling the amount of light that enters the eye by changing its size.