B2

What is the cell cycle?

A process for cell growth, DNA replication, and division for growth and repair.

Key stages of the cell cycle?

G1 phase (growth), S phase (DNA replication), M phase (mitosis), and cytokinesis.

What happens during the G1 phase?

Cells grow larger and prepare for DNA replication.

What happens in the S phase?

DNA is duplicated, forming 46 chromosomes in humans.

What is mitosis (M phase)?

Chromosomes condense and are pulled apart, splitting into two new cells.

What is cytokinesis?

The final splitting of the cell into two identical daughter cells.

Why is cell division important?

For growth, repair, and reproduction.

What is mitosis used for?

Growth, tissue repair, and asexual reproduction.

What happens in the first stage of mitosis?

Chromosomes shorten, and the nuclear membrane breaks down.

What happens in the second stage of mitosis?

Chromosomes line up in the centre of the cell.

What happens in the third stage of mitosis?

Fibbers pull chromosomes to opposite sides.

What is the final stage of mitosis?

Two new nuclear membranes form around the separated chromosomes.

Why is mitosis important for growth and repair?

It replaces damaged or old cells with identical new ones.

What is cell differentiation?

The process where cells become specialized for specific functions.

What are embryonic stem cells?

Cells that can differentiate into any cell type.

What are adult stem cells?

Stem cells that mainly produce specific types of cells for repair.

What are plant stem cells?

Found in meristems, they enable continuous growth in plants.

What is active transport?

The movement of molecules from low to high concentration, using energy (ATP).

Example of active transport?

Root hair cells absorbing nutrients from the soil.

What is diffusion?

Passive movement of particles from high to low concentration without energy.

Example of diffusion?

Gas exchange in the lungs.

What factors affect diffusion?

Concentration gradient, temperature, and surface area.

What is osmosis?

The movement of water from high to low concentration across a partially permeable membrane

Is osmosis an active or passive process?

Passive process, requiring no energy.

Where does osmosis occur in plants?

Water moves into plant roots.

What is gas exchange?

The process of taking in oxygen and expelling carbon dioxide in the lungs.

What is the role of alveoli in gas exchange?

They provide a large surface area for efficient gas exchange.

Why do small organisms rely on diffusion?

They have a high surface area to volume ratio, allowing efficient diffusion.

Why do larger organisms need transport systems?

They have a lower surface area to volume ratio, limiting diffusion efficiency.

Examples of specialized exchange surfaces?

Lungs and intestines in humans, root hairs in plants.

What features make exchange surfaces efficient?

Large surface area, thin membranes, and good blood supply.

Why is a large surface area important?

It speeds up the rate of diffusion.

Why is a thin structure important?

It reduces the distance over which diffusion occurs.

What role does a good blood supply play?

It maintains concentration gradients for efficient exchange.

What is the primary function of the heart?

To pump blood and deliver oxygen and nutrients to tissues.

How many chambers does the heart have?

Four: two atria and two ventricles.

What are the two circulation loops?

Pulmonary circulation (to the lungs) and systemic circulation (to the body).

What are pacemaker cells?

Cells that regulate the heart’s rhythm.

What do coronary arteries do?

Supply oxygen-rich blood to the heart muscles.

What is the role of arteries?

To carry blood away from the heart under high pressure.

What is the role of capillaries?

To exchange nutrients and gases with tissues.

What is the role of veins?

To return blood to the heart with valves to prevent backflow.

What is unique about veins?

They have valves to ensure unidirectional flow of blood.

What do red blood cells do?

Transport oxygen using hemoglobin.

What is the role of platelets?

Help with blood clotting.

What does plasma do?

Carries nutrients, cells, and waste products.

What is the primary function of leaves in plants?

Photosynthesis and gas exchange.

What is the palisade mesophyll?

A layer in leaves packed with chloroplasts for maximum light absorption.

What are stomata?

Small openings in leaves for gas exchange.

What controls the opening and closing of stomata?

Guard cells.

What is transpiration?

The movement of water through a plant, from roots to leaves, driven by evaporation.

What is translocation?

The movement of sugars through the phloem in both directions.

What increases transpiration?

Higher light intensity, warmer temperatures, and increased airflow.

What reduces transpiration?

High humidity, which decreases the concentration gradient.

What drives transpiration?

Evaporation from leaves, creating a pulling force on water in the xylem.

How does light affect transpiration?

It opens stomata, increasing water loss through transpiration.

How does temperature affect transpiration?

Higher temperatures increase evaporation rates.

How does wind affect transpiration?

Wind removes water vapor around leaves, increasing the rate of transpiration.

What is the waxy cuticle in leaves?

A protective layer that prevents water loss.

What is the role of meristem tissue in plants?

To allow growth by producing new cells.

Why is the surface area to volume ratio important in biology?

It affects the efficiency of diffusion in organisms.

What is diffusion?

The passive movement of particles from high to low concentration.

What is the role of capillaries in the circulatory system?

They enable gas and nutrient exchange between blood and tissues.

What is the function of white blood cells?

To protect the body against infections.

What role do platelets play?

They assist in clotting to prevent blood loss.

How does a strong blood supply aid in diffusion?

It maintains concentration gradients for efficient gas and nutrient exchange.

What are xylem cells responsible for?

Transporting water from roots to leaves.

What does the phloem do?

Transports sugars from the leaves to other parts of the plant.