B1 - Cell structure and transport Flashcards
What type of cell are bacteria
prokaryotic
Two types of eukaryotic cell
plants and animals
function of cell membrane
controls movement of substances in and out of the cell
function of mitochondria
site of respiration to transfer energy to the cell
function of chloroplasts
contain chlorophyll to absorb light energy for photosynthesis
function of ribosomes
enable protein synthesis (production of proteins)
function of cell wall
strengthens and supports the cell
Genetic material in a prokaryotic cell
single loop of DNA
Pros and cons of electron microscope
- beams of electrons instead of light
- cannot view living samples
- very expensive
- higher magnification and resolution
function of red blood cell
carries oxygen around the body
three adaptations of red blood cell
- no nucleus - contains more oxyhaemoglobin
- haemoglobin - binds to oxygen
- bi-concave disc - maximises surface area
function of nerve cell
carries electrical impulses around the body
two adaptations of nerve cell
- branched endings - can make connections with other nerve cells
- myelin sheath on axon - speeds up transmission of impulses
function of sperm cell
fertilises ovum (egg)
two adaptations of sperm cells
- tail - can swim through uterus
- lots of mitochondria - lots of respiration so lots of energy for swimming long distances
function of palisade cell
carries out photosynthesis in leaf
two adaptations of palisade cell
- lots of chloroplasts - lots of photosynthesis for food
- located at top of leaf - most sunlight
function of root hair cell
absorbs minerals and water from the soil
two adaptations of root hair cell
- long projection - lots can fit together to maximise surface area to volume ratio
- lots of mitochondria - lots of respiration so energy for active transport to get minerals out of soil
Define diffusion
Net movement of particles from an area of higher concentration to an area of lower concentration along the concentration gradient. Passive process.
three factors that affect diffusion
- concentration gradient
- temperature
- membrane surface area
How are villi adapted for exchanging substances?
- long and thin - increase surface area
- one-cell thick membrane - short diffusion pathway
- good blood supply - maintain steep concentration gradient
How are lungs adapted for gas exchange?
- alveoli - large surface area
- moist membranes - increase rate of diffusion
- one-cell membranes - short diffusion pathway
- good blood supply - maintains 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 - maintain steep concentration gradient
Define osmosis
Diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
Give example of osmosis in a plant
Water moves from soil into root hair cell
Define active transport
Movement of particles from an area of lower concentration to an area of higher concentration using energy from respiration.
Why is active transport needed in plant roots?
Concentration of mineral ions in the soil is lower than the concentration inside the root hair cells so mineral ions have to move against the concentration gradient to enter.
Why is active transport needed in the small intestine?
So sugars can be absorbed when the concentration of sugar in the small intestine is lower than the concentration of sugar in the blood.
