cell biology and transport

What are two types of eukaryotic cell?

animal and plant

What type of cell are bacteria?

prokaryotic

Where is DNA found in animal and plant cells?

In the nucleus

What is the function of the cell membrane?

controls movement of substances in and out of the cell

What is the function of mitochondria?

site of respiration to transfer energy for the cell

What is the function of chloroplasts?

contain chlorophyll to absorb light energy for photosynthesis

What is the function of ribosomes?

enable production of proteins (protein synthesis)

What is the function of the cell wall?

strengthens and supports the cell

What is the structure of the main genetic material in a prokaryotic cell?

Single loop of DNA

How are electron microscopes different to light microscopes?

electron microscopes use beams of electrons instead

of light, cannot be used to view living samples, are

much more expensive, and have a much higher magnification and resolution

What is the function of a red blood cell?

carries oxygen around the body

Give three adaptations of a red blood cell.

no nucleus, contains a red pigment called

haemoglobin, and has a bi-concave disc shape

What is the function of a nerve cell?

carries electrical impulses around the body

Give two adaptations of a nerve cell.

branched endings, myelin sheath insulates the axon

What is the function of a sperm cell?

fertilises an ovum (egg)

Give two adaptations of a sperm cell.

Tail for swimming ,enzymes in the head to penetrate the egg, lots of mitochondria for energy

What is the function of a palisade cell?

carries out photosynthesis in a leaf

Give two adaptations of a palisade cell.

lots of chloroplasts, located at the top surface of the leaf

What is the function of a root hair cell?

absorbs minerals and water from the soil

Give two adaptations of a root hair cell.

long projection, lots of mitochondria

What is diffusion?

net movement of particles from an area of high

concentration to an area of low concentration along a

concentration gradient – this is a passive process (does not require energy from respiration)

Name three factors that affect the rate of diffusion.

concentration gradient, temperature, membrane surface area

How are villi adapted for exchanging substances?

long and thin – increases surface area

one-cell-thick membrane – short diffusion pathway

good blood supply – maintains a steep concentration gradient

How are the lungs adapted for efficient gas exchange?

alveoli – large surface area

moist membranes – increases rate of diffusion

one-cell-thick membranes – short diffusion pathway

good blood supply – maintains a steep concentration gradient

How are fish gills adapted for efficient gas exchange?

large surface area for gases to diffuse across

thin layer of cells – short diffusion pathway

good blood supply – maintains a steep concentration gradient

What is osmosis?

diffusion of water from a dilute solution to a

concentrated solution through a partially permeable membrane

Give one example of osmosis in a plant.

water moves from the soil into the root hair cell

What is active transport?

movement of particles against a concentration

gradient – from a dilute solution to a more

concentrated solution – using energy from respiration

Why is active transport needed in plant roots?

concentration of mineral ions in the soil is lower than

inside the root hair cells – the mineral ions must move

against the concentration gradient to enter the root hair cells

What is the purpose of active transport in the small intestine?

sugars can be absorbed when the concentration of sugar

in the small intestine is lower than the concentration of sugar in the blood