Transport Systems Flashcards
3 points
why is there a need for transport systems
cells require essential substances such as nutrients and oxygen
in a multicellular organism, most cells lie far from the source of the essential substances
an efficient way is required for cells in multicellular organisms to obtain these substances
4 points
how is water absorbed in a plant
root hair cell sap has a lower water potential than surrounding soil water and water moves in by osmosis
water moves from cell to cell down a water potential gradient until it reaches the cells surrounding the root xylem vessels
cells surrounding xylem vessels pump ions into xylem vessel by active transport, lowering water potential of vessels
water from surrounding living cells moves into xylem vessels by osmosis
2 points
how are mineral salts absorbed in a plant
when concentration of ions is higher in surrounding soil solution than root hair cell, ions diffuse into root hair cell
when concentration of ions is higher in root hair cell than surrounding cell solution, minerals move into cell by active transport which requires energy
2 points
how are root hair cells adapted for their functions
it is long and narrow to increase surface area to volume ratio
this increases the rate of absorption of water and dissolved mineral salts from soil into plants
3 points
describe the vascular bundle
arranged in a ring around central region
phloem lies outside the xylem with a tissue called cambium between them
cambium cells can divide and differentiate to form new xylem and phloem tissues, giving rise to a thickening of the stem
2 points
what are the functions of xylem vessels
conducts water and dissolved mineral salts from roots to stem and leaves
provides mechanical support for plant
3 points
what is the structure of xylem vessels
made up of many dead cells fused together at the ends to form a long hollow tube
has continuous lumen with no cross-walls or protoplasm
lignin deposits in walls of xylem vessels
2 points
how are xylem vessels adapted for their functions
hollow lumen enables water to move through easily
walls lignified to prevent collapse of individual vessels
1 point
what is the function of the phloem
transports manufactured food (e.g. sucrose & amino acids) from leaves to other parts of plant
5 points
what is the structure of the phloem
consists of mainly sieve tubes and companion cells
sieve tube cells are elongated cells that lack nuclei and have thin layers of cytoplasm
sieve tube cells joined end to end to form a column with sieve plates in between
sieve plates are cross-walls with many small sieve pores
companion cells are narrow, thin-walled cells with cytoplasm, nucleus and numerous mitochondria
how is the phloem adapted for its function
companion cells have numerous mitochondria that release energy for the transfer of sugars into the phloem sieve tubes
what is the use of the circulatory system
allows for quick transportation of nutrients and oxygen to all body parts so that the body can produce energy rapidly
3 points
what does the circulatory system consist of
heart
blood vessels (arteries, veins, capillaries)
blood (transport medium)
what is the function of veins
carries deoxgenated blood towards the heart
what is the function of arteries
carries oxygenated blood away from the heart
what is the function of capillaries
connects arteries to veins, site of exchange of substances
6 points
how is blood transported through the heart
deoxygenated blood returns to the heart via the vena cava
right atrium contracts and blood flows into the right ventricle
right ventricle contracts and blood leaves through pulmonary arteries to lungs
oxygenated blood from the lungs flows to left atrium via pulmonary veins
left atrium contracts and blood flows into left ventricle
left ventricle contracts and blood flows through aorta to rest of body
how does blood act as a transport medium
blood is a fluid tissue, consisting of plasma, red blood cells (erythrocytes), white blood cells and platelets
2 points
what are the functions of plasma in blood
solvent for many substances
transports:
1) digested food from small intestine to other parts of body
2) carbon dioxide and other waste substances produced in body cells
3) other substances such as hormones
3 points
how are red blood cells (erythrocytes) adapted to its functions
biconcave in shape:
- increases surface-area-to-volume ratio
- take in or release oxygen at a faster rate
contains haemoglobin:
- allows oxygen to be carried as oxyhaemoglobin
enucleate (nucleus absent):
- more room for haemoglobin
3 points
what are the characteristics and function of white blood cells
kill bacteria or pathogens
colourless as they do not contain haemoglobin
have nucleus and larger than red blood cells
2 points
what are the characteristics and function of platelets
fragments of cytoplasm (surrounded by membrane)
plays an important role in blood clotting
3 points
how does the exchange of gases occur at the lungs
air is conveyed to the lungs by a system of branching ducts which end with alveoli (air sacs)
exchange of gases occurs at the alveoli in the lungs by diffusion
when our body cells respire, they make use of oxygen and produce carbon dioxide as waste substance
