b1 Flashcards
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, contains lots of mitochondria.
What is the function of a palisade cell?
carries out photosynthesis in a leaf
Give two adaptations in 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 surfaces?
- 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
