Explanation

• The nucleus is the control center of the cell.
• It regulates all vital activities like growth, reproduction, and metabolism.
• It contains genetic material (DNA).
• Ribosomes make proteins, and cytoplasm supports cell structure.

Last verified on 04-05-2026

Explanation

• Peroxisomes contain enzymes that break down harmful substances and help protect cells from toxic compounds.
• They break down hydrogen peroxide (H₂O₂) into water and oxygen using the enzyme catalase.

Additional information:

• Golgi body modifies, packages, and transports proteins.
• Lysosomes digest waste materials and worn-out cell components.

Last verified on 25-10-2026

Explanation

• Homeostasis is the ability of an organism to maintain a relatively stable internal environment despite changes in external conditions.
• It regulates body temperature, blood glucose levels, water balance, and blood pH.
• The nervous system and endocrine system work together to regulate many homeostatic processes, mainly through negative feedback.

Last verified on 25-10-2026

Explanation

• The pharynx passes air into the larynx.
• It is the voice box.
• It is part of the respiratory system.
• The glottis is the opening between the vocal folds that allows air to pass through the larynx.
• The larynx directs air into the trachea, which carries it toward the bronchi and lungs.
• Air pathway: Pharynx → Larynx → Trachea → Bronchi → Lungs.

Last verified on 25-10-2026

Explanation

• Peripheral proteins are located on the inner or outer surface of the cell membrane.
• They are not embedded deeply in the lipid bilayer.
• They perform important functions, including cell signalling, enzymatic activity, and supporting the cell membrane.

Additional information:

• Integral proteins, in contrast, are embedded within the lipid bilayer and may extend across the entire membrane.
• Plasmodesmata are microscopic channels connecting adjacent plant cells, allowing substances and signals to pass between them.

Last verified on 25-10-2026

Explanation

• Paleontology: The scientific study of fossils and ancient life.

Additional information:

• Archaeology: The study of past human societies through material remains.
• Geology: The study of Earth's structure, rocks, and processes.
• Anthropology: The study of humans, their evolution, and cultures.

Last verified on 25-10-2026

Explanation

Oxidation number of Cr in Na2Cr2O7:

Let oxidation number of Cr = x

2(Na) + 2(Cr) + 7(O) = 0

2(+1) + 2(x) + 7(-2) = 0

2 + 2x -14 = 0

2x = 12

x = +6

Last verified on 25-10-2026

Explanation

• James Chadwick discovered the neutron in 1932.
• A neutron is a subatomic particle with no electric charge, found in the nucleus of an atom.
• He received the 1935 Nobel Prize in Physics for this discovery, which greatly improved scientific understanding of atomic structure.
• Neutrons help stabilize atomic nuclei.

Last verified on 25-10-2026

Explanation

• Antimony is a chemical element with the symbol Sb and atomic number 51.
• The symbol Sb comes from the Latin name Stibium.
• Antimony is a metalloid used in alloys, flame-retardant materials, and some semiconductor applications.

Additional information:

• Au — Gold: Atomic number 79.
• Ag — Silver: Atomic number 47.
• Fe — Iron: Atomic number 26.
• Na — Sodium: Atomic number 11.
• K — Potassium: Atomic number 19.

Last verified on 25-10-2026

Explanation

• Hess's law states that the total enthalpy change of a chemical reaction is the same regardless of whether the reaction takes place in one step or several steps.
• Enthalpy change depends only on the initial reactants and final products, not on the pathway followed by the reaction.
• The law is based on the fact that enthalpy is a state function, meaning its value depends on the initial and final states.

Last verified on 25-10-2026