Nucleus

Controls all the activities of the cell.  It contains the genes on the chromosomes.  They carry the instructions for making new cells or new organisms.

Cytoplasm

A liquid gel in which most of the chemical reactions needed for life take place.

Cell Membrane

Controls the passage of substances into and out of the cell

Mitochondria

Structures in the cytoplasm where oxygen is used and most of the energy is released during respiration

Ribosomes

Where protein synthesis takes place.  All the proteins needed in the cell are made here.

Cell Wall

Made of cellulose which strengthens the cell and gives it support.

Chloroplasts

Found in all the green parts of the plant.  They are green because they contain a green substance called chlorophyll.

Chlorophyll

Absorbs light energy to make food by photosynthesis.

Permanent Vacuole

A space in the cytoplasm filled with cell sap.  This is important for keeping the cells rigid to support the plant.

What are the main features found in all living cells?

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

How do plant cells differ from animal cells?

Plant cells have all the features that animal cells have, but they also contain a cell wall, chloroplasts and a permanent vacuole.

How are bacteria different from animal and plant cells?

Unlike animal and plant cells, the genes in a bacterial cell are not contianed in a nucleus.  The long strand of DNA is usully circular and is found free in the cytoplasm.

How do yeast cells differ from bacteria cells?

Yeast cells are bigger than bacteria, but still very small.  They also reproduce by asexual budding.

What is asexual budding?

A form of asexual reproduction where a complete new individual forms as a bud on the parent organism.

Aerobic Respiration

Breaking down food using oxygen to release energy for the cells.

Fermentation

The reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide.

How are fat cells specialised?

• They have a small amount of cytoplasm and large amounts of fat
• They have few mitochondria as the cell needs very little energy
• They can expand - a fat cell can end up 1000 times its original size as it fills up with fat

How are cone cells specialised?

• The outer segment contains a special chemical which changes chemically in coloured light
• The middle segment is packed full of mitochondria to release the energy needed to reform the pigment
• They have specialised synapses that connect to the optical nerve which pass impulses to the brain

How are root hair cells specialised?

• They have lots of little hairs on the surface to increase the surface area for water to move into the cell
• They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil across the cell

How are sperm cells specialised?

• A long tail that whips from side to side and helps it move towards the egg
• The middle section is full of mitochondria, which provides the energy for the tail to work
• The acrosome stores digestive enzymes for breaking down the outer layers of the egg
• A large nucleus contains the genetic information to be passed on

What is diffusion?

Diffusion is the spreading out of the particles of a gas, or of any substance in solution.  This results in the overall movement of the substance.  This movement id from high concentration to low concentration.

What affects the rate of diffusion?

The greater the difference in concentration, the faster the rate of diffusion.

The difference between two areas of concentration is called the concentration gradient.

What is a tissue?

A tissue is a group of cells with similar structure and function working together.

e.g. muscle tissue, glandular tissue, mesophyll tissue

What is an organ?

Organs are made up of tissues.  One organ can contain several tissues, all working together.  For example, the stomach is an organ involved in digesting food.  It contains muscular tissue, glandular tissue and epithelial tissue

What is the digestive system and what does it do?

The digestive system in a mammal is an example of a system where substances are exchanged with the environment.

What is an organ system?

Organ systems are groups of organs that perform a particulr function.

What are the main organs in a plant?

Plant organs include stems, roots and leaves.

What is the function of the stem?

Provides support in plants

What is the function of the roots?

Anchoring plants and obtaining water and minerals from the soil

What is the function of the small intestine?

Breaking down large insoluble molecules into smaller soluble molecules

What is the function of the leaf?

Photosynthesising in plants