Explanation

A gene is a small segment of DNA that contains the information needed to encode a single protein.

It is the basic unit of heredity and is made up of a sequence of nucleotides (DNA building blocks) that are organized into codons, which specify the amino acids that make up a protein.

Explanation

Plants exchange gases through:

• Roots: absorb oxygen and release carbon dioxide through small openings called root hairs
• Stomata (singular: stoma): tiny openings on leaf surfaces that allow for gas exchange (CO2 in, O2 out)
• Stem: some plants have aerial roots or stem cuticles that allow for gas exchange

Explanation

Gaseous exchange refers to the exchange of gases between an organism and its environment.

Both photosynthesis and respiration involve gaseous exchange:

• Photosynthesis: takes in carbon dioxide (CO2) and releases oxygen (O2)
• Respiration: takes in oxygen (O2) and releases carbon dioxide (CO2)

Explanation

The commutator is a crucial component in a DC motor that reverses the direction of current through the coil every half-cycle.

It is a mechanical switch that rotates with the armature.

It makes contact with the brushes, switching the current flow to the coil as the armature rotates.

Explanation

• When a light ray enters from a denser medium to a rarer medium, it bends away from the normal (a line perpendicular to the surface).

Key Points:

• Denser to rarer: Away from normal
• Rarer to denser: Toward normal

Explanation

In a concave mirror, the image size depends on the position of the object.

As the object moves closer to the mirror, the image size increases, and as it moves away, the image size decreases.

Explanation

Qc (reaction quotient) is defined as the ratio of the molar concentrations of products to reactants, each raised to the power of their respective stoichiometric coefficients (coefficients in the balanced chemical equation).

Explanation

Fermenters are also known as bioreactors.

They are large containers used to grow microorganisms like bacteria, yeast, or cells on a large scale for various industrial applications, such as:

• Production of biofuels
• Biopharmaceuticals
• Food processing
• Biotechnology research

Explanation

A reflex action is a rapid, automatic response to a stimulus.

The simplest reflex arc involves only two neurons:

1. Sensory neuron (afferent): carries information from the receptor to the spinal cord
2. Motor neuron (efferent): carries the response from the spinal cord to the effector (muscle or gland)

Key Point:

The longest reflex pathway involves multiple neurons.

It is called a "long reflex" or " polysynaptic reflex".

Explanation

A filament is a thin wire, typically made of tungsten, that is heated to produce a continuous flow of electrons.

When an electric current is passed through the filament, it heats up and releases electrons, creating a steady stream of electrons.

This principle is used in various devices such as vacuum tubes, cathode ray tubes (CRTs), and electron microscopes.