Biology 1.1 Cells

What are the components of both plant and animal cells? (4)

Nucleus

Cytoplasm

Cell membrane

Mitochondria

What are the functions of the nucleus?

Stores genetic information.

Controls cellular activities.

Describe the structure of the cytoplasm.

Fluid component of the cell.

Contains organelles, enzymes, and dissolved ions and nutrients.

What is the function of the cytoplasm?

Site of cellular reactions, e.g., the first stage of respiration.

What is the function of the cell membrane?

Controls the entry and exit of materials into and out of the cell.

What is the function of the mitochondria?

Site of later stages of aerobic respiration in which ATP is produced.

What organelles are found only in plant cells? (3)

Cell wall

Large, permanent vacuole

Chloroplasts

What is the cell wall made of?

Cellulose.

What is the function of the cell wall?

Provides strength.

Prevents the cell from bursting when water enters by osmosis.

What does the permanent vacuole contain?

Cell sap (a solution of salts, sugars, and organic acids).

What is the function of the permanent vacuole?

Supports the cell, maintaining its turgidity.

What is the function of the chloroplasts?

Site of photosynthesis.

What piece of equipment is used to observe plant and animal cells?

Light microscope.

How does a light microscope work?

Passes a beam of light through a specimen, which travels through the eyepiece lens, allowing the specimen to be observed.

Describe the pathway of light through a light microscope.

Lamp → Condenser → Specimen → Objective lens → Eyepiece lens → Eye.

What is the function of the eyepiece lens?

Magnifies the image.

Fixed magnification, usually ×10.

What is the function of the objective lens?

Magnifies the image.

Interchangeable magnifications: ×4, ×10, ×40.

What is the function of the iris diaphragm?

Adjusts the amount of light that passes through the specimen and enters the objective lens.

What is the function of the condenser?

Focuses light onto the objective lens.

How is a light microscope manually focused?

Using the coarse focus control and fine focus control.

What is the function of the coarse focus control?

Used to focus the image under the low-power objective lens.

What is the function of the fine focus control?

Used to finely adjust the focus of an image.

What is cell differentiation?

Process in which unspecialised cells (stem cells) become specialised to have a specific function.

Why is cell differentiation important?

Enables the formation of specialised cells with specific functions, e.g., sperm cells, red blood cells.

What is a tissue?

A group of similar cells that work together to perform a specific function, e.g., muscle tissue, xylem tissue.

What is an organ?

A group of tissues that work together to perform a specific function, e.g., brain, heart, kidney.

What is an organ system?

A group of organs that work together to perform a particular function, e.g., nervous system, digestive system.

What is an organism?

A living thing that is able to function independently, e.g., human, sunflower./