Biology Y11 Topic 2

What is a cell?

The basic structural and functional unit of life.

What is a light microscope used for?

To observe cells and small structures by magnifying them using light.

What is an organelle?

A specialised structure within a cell that performs a specific function.

What is the function of the cell membrane?

Controls movement of substances into and out of the cell.

What is the function of the cell wall?

Provides support and maintains shape in plant cells.

What is the function of the nucleus?

Contains genetic material (DNA) and controls cell activities.

What is the function of the cytoplasm?

Site of chemical reactions in the cell.

What is the function of chloroplasts?

Site of photosynthesis; contains chlorophyll.

What is the function of mitochondria?

Site of aerobic respiration; releases energy.

What is the function of vacuoles?

Stores cell sap and maintains turgor pressure in plant cells.

What is the function of ribosomes?

Site of protein synthesis.

What is the function of rough endoplasmic reticulum (RER)?

Transports and modifies proteins.

What is a key difference between plant and animal cells?

Plant cells have a cell wall, chloroplasts, and a large vacuole; animal cells do not.

What is magnification?

How many times larger an image is compared to the actual size.

What is the formula for magnification?

Magnification = image size ÷ actual size.

What unit conversions are commonly used in microscopy?

1 mm = 1000 µm.

What is a tissue?

A group of similar cells working together to perform a function.

What is an organ?

A structure made of different tissues working together.

What is an organ system?

A group of organs working together to perform a major function.

What is the order of organisation in living organisms?

Cell → tissue → organ → organ system → organism.

How is a ciliated cell adapted to its function?

Has cilia to move mucus and trapped particles.

How is a root hair cell adapted?

Has a long extension for large surface area to absorb water and minerals.

How is a xylem vessel adapted?

Hollow tubes with thick walls to transport water and provide support.

How is a palisade mesophyll cell adapted?

Contains many chloroplasts for efficient photosynthesis.

How is a nerve cell adapted?

Long axon for transmitting electrical impulses.

How is a red blood cell adapted?

Biconcave shape and no nucleus to carry oxygen efficiently.

How is a sperm cell adapted?

Has a tail for movement and many mitochondria for energy.

How is an egg cell adapted?

Large with nutrient stores for early development.

What is diffusion?

The net movement of particles from high to low concentration down a concentration gradient.

What causes diffusion?

Random movement of particles using their own kinetic energy.

Where does diffusion occur in cells?

Across the cell membrane.

What factors increase the rate of diffusion?

Higher temperature, larger surface area, steeper concentration gradient, shorter distance.

How does temperature affect diffusion?

Higher temperature increases particle movement, speeding diffusion.

How does surface area affect diffusion?

Larger surface area increases rate of diffusion.

How does distance affect diffusion?

Shorter distance increases rate.

What is osmosis?

Diffusion of water from high water potential to low water potential through a partially permeable membrane.

What is water potential?

The tendency of water molecules to move from one area to another.

What does “partially permeable membrane” mean?

Allows some substances (like water) to pass through but not others.

What does turgid mean?

A plant cell swollen with water, firm due to turgor pressure.

What is turgor pressure?

Pressure of water pushing against the cell wall.

What does flaccid mean?

A plant cell that has lost water and is limp.

What is plasmolysis?

When the cell membrane pulls away from the cell wall due to water loss.

What happens to plant cells in a hypotonic solution?

Water enters, cell becomes turgid.

What happens to plant cells in a hypertonic solution?

Water leaves, cell becomes flaccid or plasmolysed.

Why is osmosis important in plants?

Helps maintain support and allows water uptake.

What is active transport?

Movement of substances from low to high concentration using energy.

What type of gradient does active transport go against?

Concentration gradient.

What is required for active transport?

Energy (ATP) from respiration.

What role do proteins play in active transport?

Carrier proteins move ions or molecules across membranes.

Where does active transport occur in plants?

Root hair cells absorbing mineral ions.