all7. Flashcards
Function of cholesterol
stabilise the membrane OR maintain / affect / control / AW,
fluidity OR reduces permeability to, polar / charged, particles
Function of protein / glycoprotein / intrinsic protein / protein channel /
protein pump / transport protein / carrier protein
allow communication across membrane OR allow, polar /
charged, particles to pass through membrane
Function of phospholipid (bilayer) / phospholipid head
to act as a barrier (to, polar / charged, particles) / select
what enters or leaves cell
Definition: cell signalling
communication between cells
cell, recognition / identification;
cells work together / coordination between action of different cells;
to trigger, response / reaction ( inside the cell
how a glycoprotein can act as a receptor
(receptor) specific shape / described;
complementary to (shape of), trigger / named trigger /
communicating;
molecule;
(trigger / AW) binds / attaches to receptor
why there was no transmission of light after the beetroot had been placed in water at 100 °C
cell surface / plasma, membrane damaged;
pigment, released / leaks out;
pigment, absorbs / takes up, the light;
The loss of water from the aerial parts of a plant is known as…
transpiration
Water is transported up the stem in
The…
xylem
From the air spaces in the leaf, the water vapour diffuses out of the leaf through
The….
stoma(ta) / stomatal pore
Explain why water loss from the leaves of a plant is unavoidable
stomata (open to) allow, gaseous exchange / carbon dioxide in /
oxygen out / AW;
(gaseous exchange) for photosynthesis;
(photosynthesis) essential for plant to, gain energy / make sugars;
some water lost through cuticle
the type of plant adapted to reduce water loss from its leaves
xerophyte
State and explain two adaptations of leaves that reduce evaporation
A 1] hairy leaves;
trap water vapour / moisture;
[A 2] stomata, in pits / sunken;
pits trap, water vapour / moisture;
[A 3] rolled leaves / presence of hinge cells;
reduce surface area OR (rolled leaves) trap water vapour /
moisture;
[A 4] high solute concentration in cells;
reduces water potential inside leaf cells;
[A 5] thick(er) cuticle;
(which is) waterproof / (relatively) impermeable;
[A 6] small leaves / needles; smaller surface area; [A 7] fewer stomata; reduces diffusion (of water vapour); [A 8] stomata close, during the day; reduces diffusion (of water vapour); [A 9] most stomata on lower surface; less exposure to sun OR cooler OR reduces diffusion (of water vapour); A 10] more densely packed spongy mesophyll; smaller surface area for evaporation (from mesophyll cell surface); key words: cuticle, impermeable, water vapour, potential gradient, diffuse / diffusion, stoma(ta), needles, surface area, hinge cells, saturated
Structure of prokaryotic cells
no true nucleus genetic material consists of ‘naked’ DNA average diameter of cell 0.5 – 5 µm (ribosomes) 18nm; cell wall (present);
Structure of eukaryotic cells
genetic material held in a nucleus as chromosomes / chromatin OR (genetic material) associated with, proteins / histones; (diameter of cell) 20 – 40 µm; ribosomes about 22 nm in diameter cell wall sometimes present
structure, associated with the cytoskeleton, which can bring about cell movement
flagellum / cilium / microtubule / microfilament / undulipodium
processes inside cells that rely on the cytoskeleton for movement
(movement inside cells of) chromosomes / chromatids (in cell division); (cytoplasm in) cytokinesis; organelles / named organelle; RNA (in protein synthesis); proteins;
During stage S, the genetic information is copied and checked.
Suggest what might happen if the genetic information is not checked
mutation / faulty DNA produced / error in copying;
daughter cells will not receive identical genetic information;
proteins / (daughter) cells, not made / do not function
During meiosis a cell undergoes two divisions.
Suggest how cells produced by meiosis may differ from those produced by mitosis
haploid / half genetic information / chromosome number is n;
genetic information not identical / produces genetically different
cells;
4 cells produced;
the type of muscle found in the walls of the heart chambers
cardiac
the process that creates pressure inside the heart chambers
muscle) contraction / systole
Golgi apparatus function
repackage / transport, proteins;
add carbohydrate group to protein
Ribosome function
site of protein synthesis
how the structure of the sperm cell is specialised for carrying out its role
flagellum for movement;
chromosomes / DNA, in haploid nucleus / AW, for fertilising egg cell;
head / cap / acrosome, shaped for penetrating egg cell (membrane);
(many) mitochondria for energy / ATP, for movement
Definition: tissue
group of cells;
of one or more types; A ‘common origin’
with intercellular material/connective tissue / AW;
(specialised) to perform particular function(s);
Example of a plant tissue
xylem / phloem / epidermis / mesophyll / palisade / spongy mesophyll /
chlorenchyma / etc./ meristem / cambium / suitable named tissue
the approximate width of the membrane
7nm;
Structure of phospholipid
hydrophilic / polar/AW, head;
hydrophobic / non-polar / AW tail
Function of channel protein
allow, small / charged, molecules through membrane
roles of glycoproteins in membranes
stabilises membrane structure by forming hydrogen bonds with water
molecules;
antigens for cell recognition;
binding sites, for, chemicals/ drugs / hormones / neurotransmitters/
antibodies /T cells;
receptors for cell signalling / triggers chemical reactions inside cell;
Glycoprotein structure
a protein embedded in the membrane with a branched carbohydrate chain projecting out from the surface of the cell
Why single-celled organisms generally have a larger surface-area to volume ratio
living cells need to take in oxygen/ nutrients and remove (metabolic)
waste;
ref. passive processes / diffusion;
rate of diffusion too slow if SA:V ratio too small;
The lungs in the mammalian body are well developed to allow effective exchange of gases.
Describe the features of the lungs that make them effective organs for the exchange of gases
many alveoli to produce large surface area;
barrier, thin / only two cells thick;
good blood supply / many capillaries;
to carry dissolved gases to and from the alveoli;
ventilation / air movement to refresh the air in the alveoli;
(contains) elastic tissue to stretch and recoil to help expel air;
why the volume of air in the spirometer drops slowly over the first minute
oxygen is used in respiration;
carbon dioxide is released ( in respiration);
carbon dioxide is absorbed (by soda lime);
Definition: double circulatory system
blood flows) twice through the heart / AW;
for one circuit / cycle (of the whole body) / AW; A for one heart beat
ref pulmonary and systemic systems / to lungs and to (rest of) body;
why the wall of chamber the left ventricle is much thicker than the walls of chambers of the right atrium and the right ventricle
provides more, force / pressure, to pump blood around body;
longer distance compared with distance right ventricle has to pump blood;
or right atrium
Haemoglobin, a pigment found in the blood of mammals, has an important role in the…
transport of respiratory gases
Each haemoglobin molecule contains…
Haem groups
In the lungs, oxygen binds with the atom of… in each haem group
iron
The maximum number of molecules of oxygen that can be carried by one molecule of haemoglobin is…
4
In areas like muscle tissue where the partial pressure of oxygen is low…
oxygen dissociates from the haem group
This dissociation is increased by the presence of carbon dioxide; this is called the…
Bohr, effect / shift
Most of the carbon dioxide produced in respiring tissues diffuses into the red blood cells where the enzyme…. catalyses a reaction leading to the production of hydrogen ions and hydrogen carbonate
ions
carbonic anhydrase
. The hydrogen ions combine very readily with haemoglobin to form a compound
known as…. The effect of this is to increase
the release of oxygen from haemoglobin.
haemoglobinic acid
Transpiration itself is not measured directly by a potometer.
State what is measured by this apparatus
water uptake
Describe how the potometer should be set up to ensure that valid measurements can be made
1 cut (healthy) shoot under water (to stop air entering xylem vessels);
2 cut shoot at a slant (to increase surface area);
3 check apparatus is full of water / is air bubble free / no air locks;
4 insert shoot into apparatus under water / AW;
5 remove potometer from water and ensure, airtight / watertight,
joints around shoot;
6 dry leaves / AW; max 4
7 keep, condition(s) / named condition(s), constant;
8 allow time for shoot to acclimatise / AW;
9 shut screw clip;
10 keep ruler fixed and record position of air bubble on scale;
R ‘move bubble to end’ ideas
11 start timing and, measure / calculate, distance moved per unit time
In coastal regions, unusually high tides can cause flooding of land that is not normally covered by sea water.
Explain how plants living in these regions would be affected by the change in water potential (Ψ) of the soil caused by such flooding.
1 (water moves) by osmosis;
2 down water potential gradient/from high Ψ to low Ψ;
(less negative to more negative)
3 sea water has low water potential/(soil) water potential decreased;
(more negative)
4 Ψ, gradient reduced/lower than inside, root/cells/plant;
5 plant, loses/can’t absorb (as much), water;
6 cells, flaccid/lose turgor;
7 plasmolysis/described;
8 wilting/poor growth; in correct context
Outline the roles of membranes at the surface of cells and within cells.
at surface
S1 separate cell from environment;
S2 control, entry/exit (of molecules/ions/suitable substance);
A selective/partial R semi-permeable
S3 use of phospholipid layer (in allowing or preventing passage) of
suitable example;
S4 reference to facilitated diffusion;
S5 reference to active uptake; R channel protein
S6 reference phagocytosis/pinocytosis/endocytosis/exocytosis;
S7 cell recognition/cell surface antigens;
S8 cell to cell attachment;
S9 receptor (for hormones/neurotransmitters etc.);
S10 AVP; microvilli increase surface area of cell
enzyme attachment
further role max 6
within W1 compartmentalise/surrounds organelles; W2 prevents disruption of, reactions/process; A reaction more efficient W3 e.g. reaction/process, and organelle; W4 reactions take place on membranes; A named example of membrane W5 enzymes attached to membranes; A named example W6 isolates/separates, DNA/nucleus;
W7 (nuclear pore) permits RNA to leave nucleus;
W8 (forms) ER/(Golgi) vesicles/lysosomes/other named organelle;
(not the same e.g. as W3 or W6)
W9 attachment of ribosomes;
W10 intracellular transport;
W11 protects cells from contents of lysosomes;
W12 (tonoplast) surrounds/controls content of, vacuole;
W13 AVP; increases (internal) surface area of organelle
attachment of pigments
formation of mesosomes
why liver cells of the type shown in the diagram contain many mitochondria
(liver requires) a lot of, energy/ATP
The haploid number of chromosomes for a human is 23.
(i) State the number of chromosomes present in the nucleus of the liver cell
46/23 pairs
the type of nuclear division that produced this liver cell
mitosis
