Explanation

In plants, the cell wall is primarily composed of strong fibers of cellulose, a type of carbohydrate.

Cellulose is a polymer of glucose molecules that provides structural support, rigidity, and protection to the plant cell.

Explanation

Dentists use concave mirrors to illuminate inaccessible places in the tooth.

The concave shape of the mirror allows it to reflect light and images from small, hard-to-reach areas.

Such as the back of the mouth or between teeth.

Explanation

When a wave passes from one medium to another, its frequency remains unchanged.

However, its speed, wavelength, and direction may change.

Explanation

Mass is not a characteristic of a wave.

The characteristics of a wave include:

• Amplitude (the maximum displacement of the wave from its equilibrium position)
• Period (the time taken by the wave to complete one oscillation)
• Velocity (the speed at which the wave travels)
• Wavelength (the distance between two consecutive points on the wave that are in phase)
• Frequency (the number of oscillations per unit time)

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

Chlorine can be displaced by fluorine (F).

This is because fluorine is more reactive than chlorine.

As halogen reactivity decreases down the group in the periodic table.

Explanation

In a Daniell cell, the following is used as a cathode:

• Copper (Cu): The copper electrode is reduced and gains electrons to form copper atoms.
• The half-reaction is: Cu2+(aq) + 2e- → Cu(s)

Explanation

The molar mass of sodium chloride (NaCl) is 58.44 g/mol.

To find the mass of 2 moles of NaCl, you can multiply the molar mass by 2: 2 mol × 58.44 g/mol = 116.88 g

Rounded to the nearest gram, this is approximately 117 grams.