questions ive got wrong Flashcards
in nucleotides, what components contain carbon
- pentose sugar
- nitrogen containing bases
what is the role of cholesterol
-binds to phospholipids fatty acid tails, increasing packing of membrane thus reducing the fluidity of the membrane.
why do single celled organisms not need a specialised surface for gaseous exchange
- its a single cell ( has a large sa to vol ratio)
- it has a short diffusion pathway- easy for gasses to diffuse in and out
describe the structure of the plasma membrane
-primarily made of phospholipid bilayer that contains proteins. hydropho9bic tails face inwards and hydrophilic heads face outwards. cholesterol bound to fatty acid tails. Extrinsic and intrinsic proteins present. Glycoproteins stick out the bilayer.
why are different enzymes involved in different processes
enzymes are SPECIFIC and the substrates have diff shapes. the active site and a substrate have to be complimentary to form ESC.
what forms enzyme product complex
destabilizing of bonds
what improves reliability
-repeating experiment
explain the induced fit hypothesis
- active site changes shape so a closer fit occurs (more bonds form between active site and and substrate)
- forms ESC
- destabilising of bonds forms EPC
- activation energy reduced
- active site changes again when product leaves
what is the detailed structure of cells visible with only an electron microscope
ultrastructure
what do xylem vessels contain
lignin
2 types of cells found in phloem tissue
-companion cells and sieve tube elements
how to see amino acids in chromatography
spray with ninhydrin
what are the coils of amylose and amylopectin held by?
hydrogen bonds
difference in amino acid structure in fibrous and globular
fibrous- repetitive amino acid sequence
globular- varied in amino acids- hydrophilic and hydrophobic
what can stem cells be used for
- asexual reproduction
- growth of organism
- repair of damaged tissues
whats the point of lignin
- to waterproof the cell which improves adhesion of water
- strengthens the cell to prevent collapse of xylem
- ( for some)spiral pattern allows for flexibility
whats the function of bordered pits
allow water to move between xylem vessels, lateral flow and allow for supply of water through the plant and to other cells
state 3 roles of membranes inside cells
- cell compartmentalisation
- provide selective permeability
- site of attachment for enzymes
whats the term organ
more than 1 type of tissue working with many tissues to perform a specific function
what side does the bhor shift cause the sigmoid to move
to the right
what allows for the movement of cillia
what structure allows for secretion of mucus
- cytoskeleton
- centriole
how is hydrostatic pressure generated in the heart
by the contraction of ventricles
explain why the hydrostatic pressure drops as u move away from the heart
as you move away, there are more smaller vessels, the vessels have a larger total lumen. Arteries can also stretch and expand and at the capillaries, there is loss of fluid.
describe how the action of the heart is initiated and coordinated
-SAN initiates impulse which is excitation across the atrial walls causing the atria to contract (atrial systole). The impulse is then received at the AVN, delayed then conveyed down the bundle of His into the purkinje fibres which reach along the apex of the heart causing the ventricle to contract bottom upwards
whats a source
source= where sucrose and assimilates are loaded into the phloem
whats a sink
sink= where sucrose and assimilates are unloaded from the phloem
What thing do plants need if they have a low sa to vol ratio
a transport system
what pressure does transpiration produce
negative pressure
whats the function of the bordered pits
to allow water to move between vessels, can bypass blockage
-also supplies water to other tissues/cells
what do plasmodesmata allow for
flow of substances between cytoplasm of diff cells
whats transpiration
the evaporation of water from the leaves of a plant
whats the role of elastic fibers during ventilation
- to prevent bursting
- to allow for recoil
- returns air sac to its original shape and size to help expel air
how does refreshing of air in the air sacs maintain a diffusion gradient
it increases partial pressure of oxygen in the air sacs so conc is higher than that in the blood. It decreases partial pressure of CO2 in the air sac so conc of CO2 in the air sac is lower than that in the blood
in terms of binomial name, what does the 1st part tell us
the genus
in terms of binomial name, what does the 2nd part tell us
the species
how does histamine stimulate smooth muscle contraction
-histamine binds to a receptor on the plasma membrane of a muscle cell which produces a response
Another action of histamine is to make capillary walls more permeable.
Suggest two effects this increased permeability may have on the surrounding tissues
- more tissue fluid is formed
- oedema occurs
- more white blood cells can pass into tissues
- larger molecules pass into the tissue fluid.
tell the difference between the domain system and the 5 kingdom system
- for the domain system, bacteria and archaea are split into two groups because they are different.
- the domain system is based on differences in DNA
- domain groups eukaryotes together