B1 cell structure and transport Flashcards
what is the equation for magnification
size of image / size of real object
what is magnification
how many times larger the image is than the real object
advantages of an electron microscope
a better resolution
structures inside mitochondria and chloroplasts can be seen and scientists can understand how they work
ribosomes can be seen and their role of making proteins can be studied
what is the function of a nucleus
controls cell activities and contains the genetic material
what is the function of the cytoplasm
where all chemical reactions take place
what is the function of the cell membrane
controls the passage of substances coming in and out the cell
what is the function of mitochondria
where aerobic respiration takes place
what is the function of ribosomes
where proteins are synthesized
what is the function of a cell wall
made of cellulose which strengthens the cell
what is the function of the vacuole
filled with cell sap and keeps the cell rigid
what is the function of chloroplasts
contain a green substance called chlorophyll and this absorbs sunlight by photosynthesis
what is a bacterial cell
prokaryotic cell
name three differences between a prokaryotic cell and a eucaryotic cell
prokaryotic cells are much small
the genetic material is not enclosed in a nucleus
genetic material is a single loop of DNA called plasmids
they do not contain mitochondria or chloroplasts
what is a flagella
tail like structure which moves the bacterium
what adaptions does a nerve cell have
long axons carry the nerve impulse from one place to another
Dendrites make connections to other nerve cells
the nerve endings or synapses are adapted to pass the impulses to another cell or between a nerve cell and a muscle in the body using special transmitter chemicals
what adaptions does a muscle cell have
they contain special proteins which slide over each other which make the fibers contract
they contain many mitochondria which are needed to transfer the energy for chemical reactions that take place as the cell contract and relax
they contain glycogen, a chemical which can be broken down and used in cellular respiration by the mitochondria to transfer energy needed for fibers to contract
what adaptions do sperm cells have
a long tail which moves to side to side to move through water or the female reproductive system
the middles section is full of mitochondria which transfers the energy needed for the tail to work
the acrosome stores digestive enzymes for breaking down the outside layer of the egg
a large nucleus which contains the genetic information which needs to be passed on
what adaptions do root hair cells have
increase surface area for water to move into the cell
a large vacuole which speeds up the movement of water by osmosis
they have many mitochondria which transfer the energy needed for active transport
what adaptions do photosynthetic cells have
contain chloroplast which trap light needed for photosynthesis
usually in layers in leaves and outer layer of stem to absorb as much light a possible
they have a large vacuole
what adaptions do xylem cells have
They lose their end walls so the xylem forms a continuous, hollow tube.
They become strengthened by a substance called lignin . Lignin gives strength and support to the plant
what adaptions do phloem cells have
:
Sieve tubes - specialised for transport and have no nuclei. Each sieve tube has a perforated end so its cytoplasm connects one cell to the next.
Companion cells - transport of substances in the phloem requires energy. One or more companion cells attached to each sieve tube provide this energy. A sieve tube is completely dependent on its companion cell
what is diffusion
diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration
give 3 examples of diffusion
oxygen and carbon dioxide diffuse during gas exchange lungs gills and plant leaves
urea diffuses from cells into blood plasma for excretion by the kidney
digested food molecules from small intestine diffuse into the blood
what are the factors affecting diffusion
concentration gradient
temperature
surface area of the membrane
what is osmosis
the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
what is active transport
moves substances across the concentration gradient from an area of low concentration to an area of high concentration
explain the need for exchange surfaces
and a transport system in multicellular organisms
In multicellular organisms, surfaces and organ systems are
specialised for exchanging materials. This is to allow sufficient
molecules to be transported into and out of cells for the organism’s
needs.
How is the effectiveness of gas exchange surfaces increased
The effectiveness of an exchange surface is increased by:
* having a large surface area
* a membrane that is thin, to provide a short diffusion path
* (in animals) having an efficient blood supply
* (in animals, for gaseous exchange) being ventilated.
