Explanation

Graphite is a crystalline form of the element carbon.

It consists of stacked layers of graphene.

Graphite occurs naturally and is the most stable form of carbon under standard conditions.

Explanation

• The ozone layer in the stratosphere absorbs and restricts ultraviolet (UV) radiation from the sun.
• It protecting life on Earth from harmful UV rays.

Explanation

Steel, being a solid metal, is measured by weight.

The standard unit for measuring steel is kilograms or tons, depending on the quantity.

Explanation

Isotopes are atoms with different atomic masses that have the same atomic number.

The atoms of different isotopes are atoms of the same chemical element; they differ in the number of neutrons in the nucleus.

Isotopes:

• The isotopes are a group of atoms that have the same atomic numbers but different mass numbers.
• That means all isotopes of an element have the same number of protons in their atomic nuclei and the same number of electrons in the electron cloud surrounding the nucleus.

Difference between isotopes

• Isotopes differ in the total number of neutrons present in their respective atomic nuclei.
• Thus they have different mass numbers.
• Different isotopes of the same element are having different masses.
• Protium (1 proton,1 electron, and no neutrons), Deuterium (1 proton, 1 electron, and 1 neutron), and Tritium (1 proton, 1 electron, and 2 neutrons) are examples of isotopes of Hydrogen.

Explanation

Reproduction ensures the continuation of a species by passing genetic material to offspring.

It maintains biodiversity and helps species adapt to environmental changes.

Explanation

Enzymes (e.g., ribosomes, polymerases) catalyze the assembly of proteins from amino acids during translation.

While enzymes assist in building various biomolecules, their most direct and universal role is in protein synthesis.

Explanation

Mitosis Stages:

Karyokinesis: Division of the nucleus (prophase, metaphase, anaphase, telophase).

Cytokinesis: Division of the cytoplasm (occurs after karyokinesis).

Explanation

• Omnivores are animals that eat both plants and animals.
• They have adaptations that allow them to digest and extract nutrients from a wide variety of food sources, including fruits, leaves, insects, small animals, and even carrion.
• Examples of omnivores include humans, bears, pigs, chimpanzees, and raccoons.
• Only plants: Herbivores (e.g., cows).
• Only animals: Carnivores (e.g., lions).

Explanation

Active Transport:

Requires energy (ATP) to move molecules against the concentration gradient (low → high).

Example: Sodium-potassium pump in cells.

Explanation

Ecology involves the study of animals and their interactions with the environment.

It covers how organisms adapt, survive, and relate to each other and their surroundings.