Science Quiz: Cells, Atoms, Energy

Which organelle is responsible for controlling the activities of a cell?

• Mitochondria

• Nucleus

• Ribosome

• Cell membrane

Answer explanation

The nucleus is the organelle that controls the activities of a cell by regulating gene expression and maintaining the integrity of DNA. It acts as the control center, directing cellular functions and processes.

What is the function of the mitochondria in animal cells?

• Protein synthesis

• Energy production

• Storage of genetic material

• Cell division

Answer explanation

The mitochondria are known as the powerhouse of the cell, as they are responsible for energy production through the process of cellular respiration, converting nutrients into ATP, which powers various cellular functions.

Which structure is found in plant cells but not in animal cells?

• Nucleus

• Cell wall

• Cytoplasm

• Mitochondria

Answer explanation

The cell wall is a rigid structure found in plant cells that provides support and protection. In contrast, animal cells lack a cell wall and only have a flexible cell membrane.

What is the main function of the cell membrane?

• To provide energy

• To control what enters and leaves the cell

• To store water

• To produce proteins

Answer explanation

The main function of the cell membrane is to control what enters and leaves the cell, maintaining homeostasis and protecting the cell's internal environment.

Which of the following is NOT a type of cell transport?

• Diffusion

• Osmosis

• Respiration

• Active transport

Answer explanation

Respiration is a metabolic process for energy production, not a type of cell transport. In contrast, diffusion, osmosis, and active transport are mechanisms that move substances across cell membranes.

Osmosis is the movement of water molecules from:

• A low concentration to a high concentration

• A high concentration to a low concentration

• An area of high pressure to low pressure

• The nucleus to the cytoplasm

Answer explanation

Osmosis is the movement of water molecules from an area of high concentration (more water) to an area of low concentration (less water). Thus, the correct choice is 'A high concentration to a low concentration'.

Which process requires energy from the cell to move substances against a concentration gradient?

• Diffusion

• Osmosis

• Active transport

• Facilitated diffusion

Answer explanation

Active transport is the process that requires energy from the cell to move substances against a concentration gradient, unlike diffusion, osmosis, and facilitated diffusion, which occur passively.

Which of the following is a passive process?

• Active transport

• Diffusion

• Endocytosis

• Exocytosis

Answer explanation

Diffusion is a passive process where molecules move from an area of higher concentration to an area of lower concentration without the use of energy. In contrast, active transport, endocytosis, and exocytosis require energy.

What is the smallest part of an element that retains its properties?

• Atom

• Molecule

• Ion

• Compound

Answer explanation

The smallest part of an element that retains its properties is an atom. Atoms are the basic building blocks of matter, while molecules, ions, and compounds consist of two or more atoms and do not represent a single element.

Which subatomic particle has a positive charge?

• Electron

• Neutron

• Proton

• Positron

Answer explanation

The proton is the subatomic particle that carries a positive charge, distinguishing it from the negatively charged electron and the neutral neutron. The positron, while also positively charged, is an antimatter counterpart of the electron.