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biology year 1 > Cell membranes > Flashcards

Cell membranes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Suggest why tetradotoxin is not toxic to the puffer fish.

A

channel / receptor / ion , is different ;

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2
Q

Describe the structure of a plasma (cell surface) membrane.

A

phospholipid bilayer containing proteins ;
head / hydrophilic region, facing outwards
OR
tail / hydrophobic region, facing inwards ;
ref to intrinsic and extrinsic (glyco)proteins /
described ;
idea of: glycoproteins / glycolipids, sticking out (of
bilayer / membrane);
cholesterol, inside bilayer / between phospholipids ;

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3
Q

Suggest the mechanism by which the indicator enters the cells and suggest the component of the membrane involved.

A

active transport / uptake ;

(transport / carrier) protein ;

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4
Q

The student took a small sample from suspension A and added alkaline ammonia solution. There was no colour change.
What could the student conclude about the permeability of the yeast plasma membrane?

A

not permeable to, ammonia / NH3 / ammonium /

NH4+

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5
Q

The student then took another sample from suspension A and boiled it. When this boiled suspension was centrifuged the liquid portion was yellow and the cells at the bottom were red/pink.The student suggested that the liquid in the suspension was yellow because boiling the yeast had damaged the plasma membrane, allowing the indicator out of the cells. Describe the effect of high temperature on the structure of the yeast cell membranes.

A

phospholipids / (named) molecules, vibrate more /
move around more / have more kinetic energy ;
increases, size / number, of gaps, in membrane /
between phospholipids ;
bilayer, becomes more fluid / melts ;
proteins / glycoproteins, denatured ;
QWC
phospholipid(s) bilayer
kinetic energy (ref to molecules - do not credit in ref to
membrane or cell)
denature(d) (must refer to proteins or glycoproteins)

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6
Q

The bulk transport of materials out of a cell.

A

exocytosis

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7
Q

State two functions of membranes within cells.

A

forms, vesicles / (named) organelle(s) ;
separate (contents of) organelles from cytoplasm /
compartmentalisation ;
site of (named), processes / reactions ;
provides surface for attachment (of enzymes / ribosomes) ;
control what substances, enter / leave, organelles ;

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8
Q

Describe the arrangement and functions of two named components of a cell surface membrane.

A

A1 phospholipids form bilayer /described
OR
phospholipid hydrophobic tails pointing inwards and
hydrophilic heads pointing out ;
F1 provide barrier to, large / polar /
(named) molecules OR ions
OR
described ;
A2 proteins form, pores / channel / carriers
OR
extrinsic / intrinsic / transmembrane / described,
proteins ;
F2 for (active) transport / cotransport /
facilitated diffusion
OR
enzymes ;
A3 cholesterol molecules fit, within bilayer / between
phospholipid / between fatty acids / between
(phospholipid OR hydrophobic) tails ;
F3 stabilise membrane (structure) / regulates fluidity ;
A4 glycoproteins / glycolipids , on surface / sticking out
from surface, (of cell surface membrane) ;
F4 cell signalling / receptor sites / adhesion /
antigens / recognition
OR
stabilising (cell shape) ;
QWC
award if any two terms spelt correctly and used in correct
context from:
for phospholipids accept: phospholipid, bilayer,
hydrophilic, hydrophobic
for proteins accept: protein, pore, channel, carrier,
enzyme, intrinsic, extrinsic, transmembrane,
cotransport, facilitated diffusion
for cholesterol accept: cholesterol, fatty acid,
phospholipid
for glycoprotein / glycolipid accept: glycoprotein,
glycolipid, cell signal(l)ing, receptor, adhesion,
antigen

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9
Q

Which component of a cell membrane becomes more fluid as temperature increases?

A

(phospholipid) bilayer ;

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10
Q

Which component of a cell membrane denatures as temperature increases?

A

(named) proteins ;

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11
Q

Liver cells contain membrane-bound organelles called peroxisomes. These organelles contain catalase, an enzyme that breaks down hydrogen peroxide to release oxygen gas.A student carried out an investigation on catalase using the following procedure:
• two identical sized cubes were cut from a piece of fresh liver
• one cube was frozen overnight and then defrosted• the other cube was stored in the refrigerator
• both cubes were returned to room temperature and were placed in separate test tubes containing equal volumes of 2% hydrogen peroxide solution.The student observed that the cube of liver that had been frozen and defrosted, bubbled significantly more than the cube that had been refrigerated.Suggest an explanation for this result.

A

idea that: freezing / defrosting, damages the,
peroxisome / (plasma) membrane ;
increases permeability of membrane to, enzyme / hydrogen
peroxide ;
more hydrogen peroxide broken down (so more oxygen
released) ;

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12
Q

State the term used to describe a membrane through which some substances can pass freely but others cannot.

A

partially permeable

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13
Q

State what is meant by cell signalling.

A

communication between cells ;
idea that: molecule released by one cell, attaches to /
causes change in, another cell ;

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14
Q

Explain how cell surface membranes contribute to the process of cell signalling.

A

release of signal molecule by, exocytosis / secretion
OR described ;
idea that: proteins / glycoproteins / glycolipids, act as /
have, receptors OR described ;
idea that: receptor / signal, is specific ;
idea that: shape of receptor and signal are
complementary ;
idea that: attachment of signal molecule causes change
(inside cell / on cell surface) ;
cell surface membrane allows entry of some signal
molecules ;
QWC
exocytosis, secretion / secretes / secreted, glycoprotein,
glycolipid, receptor, specific, complementary

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15
Q

Suggest one type of extracellular protein secreted at exocytosis

A

enzyme / (peptide) hormone / glycoprotein ;

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16
Q

Organelle A provides ATP which is a source of energy.

Suggest one stage during the secretion of a protein that requires energy.

A

transport vesicles to, plasma / cell surface, membrane ;

fusing vesicle to membrane / exocytosis ;

17
Q

Outline the role of the Golgi apparatus.

A

1 receives proteins from the, (R)ER / ribosomes ;
2 modify / process, proteins or make glycoproteins /
add named molecule(s) / described ;
3 (re)package / AW, into vesicles ;
4 make lysosomes ;
5 replenishes, plasma / cell surface, membrane ;
6 lipid synthesis ;

18
Q

A student wanted to observe some red blood cells under the microscope. The student placed a small sample of blood onto a microscope slide and added a drop of distilled water. When viewed at high power, the student observed that the red blood cells had burst. In a similar procedure using plant epidermis, the student observed that the plant cells did not burst. Explain these observations.

A

1 cell (cytoplasm) has a lower water potential
than (distilled) water / ORA ;
2 water moves (into cells) , down water potential gradient
/ from high  to low  ;
3 (water) enters the cell by osmosis ;
4 idea of: cell surface / plasma, membrane (of blood cell)
weak so, bursts / cannot withstand pressure
/ haemolyses ;
5 idea of: (plant) cell wall , strong / provides support,
so, does not burst / can withstand pressure ;
6 (plant) cell becomes turgid / turgidity increases, which
reduces water uptake ;
QWC
gradient, water potential, osmosis,
cell surface membrane / plasma membrane,
turgid / turgidity, (derivatives of) haemolysed

19
Q

Suggest how the student could modify the procedure to observe red blood cells without them bursting.

A

use a, salt / sugar, solution OR add solute to water ;
use a solution with the, same / similar / lower,
water potential as blood cells ;

20
Q

Oxygen enters red blood cells as they pass through the capillaries in the lungs.
Name the mechanism by which oxygen enters the red blood cells.

A

diffusion

21
Q

The cells in the epidermis of a plant root are specialised to absorb minerals from the surrounding soil.State the process by which root epidermal cells absorb minerals from the soil and describe how these cells are specialised to achieve absorption.

A 
1 active, transport / uptake ;
plus any two from:
2 cells have, extensions / hairs ;
3 thin cell wall ;
4 large / increased, surface area ;
5 many / more, mitochondria ;
6 (many) carrier proteins in cell (surface) membrane ;
22
Q

State three roles of membranes inside cells.

A

2
3
4
5
form / produce / make, compartments / organelles /
named organelles (within a cell) / AW ;
isolation / AW, of, contents (of organelle) / substance /
named substance / reactions / metabolic pathways ;
site for attachment of, enzymes /
other named molecules / ribosomes ;
provide selective permeability / described ;
creation of, concentration gradients /
specific environments / described ;

23
Q

Outline how the vesicles are moved from one organelle to another.

A

cytoskeleton / microtubule / microfilament ;
provide, pathways / tracks, (for movement) ;
(vesicle) moves along, microfilaments / microtubule ;
microtubules, extended / broken down ;
uses, ATP / (metabolic) energy

24
Q

The proteins embedded in the membranes of vesicles have different functions.
• COPI and COPII proteins are known as ‘address proteins’.
• Vesicles that transport materials from the Golgi to the rough endoplasmic reticulum (RER) are coated in COPI proteins.
• Vesicles that transport materials to the Golgi from the RER are coated in COPII proteins.
Suggest how these proteins ensure that a vesicle is transported to the correct target organelle.

A

receptor found only on, correct / target, (named) organelle ;
idea that: address protein provides a way of,
labelling / identifying / recognising, the vesicle ;
protein / COPI / COPII, has a specific shape ;
(shape of) receptor and (address) protein are
complementary ;

25
Q

Cells in the pancreas secrete proteins such as the enzymes pancreatic amylase and protease.Describe how these extracellular enzymes are secreted from the cells.

A

exocytosis ;
vesicle fuses / merges ;
(with), cell surface / plasma, membrane ;
discharging / releasing, enzyme / contents (to exterior) ;

26
Q

List three components of a cell surface membrane.

A 
phospholipids ;
proteins ;
glycoproteins ;
cholesterol ;
glycolipids ;
27
Q

Explain what is meant by the term active transport

A 
(movement of substances)
against / up , concentration gradient
or
from low to high concentration ;
using , ATP / (metabolic) energy ;
using a , transport / carrier , protein ;
28
Q

State two examples of active transport in cells.For each example, you should name the substance that is transported and the cell involved.

A 
(mineral) ions / salts / named e.g, (into) root hair (cell) ;
hydrogen ions (out of) companion cells ;
(mineral) ions / salts / named e.g, (across) endodermis ;
sucrose out of sieve tube at sink ;
29
Q

Explain why plant cells do not burst when they are left in pure water.

A 
cell wall ;
provides strength / withstands (internal) pressure /
 prevents cell membrane over expanding /
 exerts pressure potential ;
limits uptake of water ;
30
Q

Suggest how the student could construct and use a graph to obtain a better estimate of the water potential.

A

idea of:
1 plot, percentage plasmolysed against water potential
(of solution) / water potential on X axis and % plasmolysed
on Y axis ;
idea of:
2 read down from 50% plasmolysed to water potential ;
OR
idea of:
1 plot, % plasmolysed against sucrose concentration /
sucrose concentration on X axis and
% plasmolysed on Y axis ;
idea of :
2 read down from 50% plasmolysed to sucrose concentration
AND
look up equivalent water potential ;

31
Q

Suggest one change that occurred to the plasma (cell surface) membranes of the yeast cells at temperatures above 60 °C.

A

(membrane) structure disrupted ;
(phospho)lipid bilayer, melts / more fluid ;
(membrane) proteins / carrier molecules,
denatured / unable to function ;
(membrane) becomes more permeable ;

32
Q

Explain why the stained yeast cells lost their colour at higher temperatures.

A

membrane permeable (to stain) ;
methylene blue, leaked out of cells / released
to solution ;
by diffusion / down concentration gradient ;

33
Q

Membranes contain a variety of proteins. Some of these proteins are combined with carbohydrates to form glycoproteins.Describe the functions of glycoproteins in the cell surface membrane.

A

1 (acting as) antigens ;
2 identification / recognition, (of cells) as, self /
non-self / AW ;
3 cell signalling / described ;
4 receptor / binding site, for, hormone /
(chemical) signal / (medicinal / named) drugs ;
5 ref. to receptor / binding site / trigger, on
transport proteins / AW ;
6 cell adhesion / to hold cells together (in a
tissue) ;
7 attach to water molecules (to stabilise
membrane / cell)
QWC
receptor, antigen, hormone, cell signal(ling), adhesion,
recognition, facilitated diffusion, active transport

34
Q

Explain, using the term water potential, what has happened to cell M; plant cell placed in concentrated sugar solution

A

water moves out of cell ;
by osmosis ;
cell has, higher / greater / less negative, water potential (than
surrounding solution) / ORA ;
(water moves) down water potential gradient/from high to low
water potential ;

35
Q

Small non-polar substances enter cells in different ways to large or polar substances.Outline the ways in which substances, other than water, can enter a cell through the plasma (cell surface) membrane.

A 
small, non-polar substances
diffuse (through membrane / phospholipid bilayer) ;
large substances
(using), transport / carrier, proteins ;
endocytosis / phagocytosis / described ;
polar substances
through, pore / channel, proteins ;
(using), transport / carrier, proteins ;
general – must be used in correct context, each once only
ref to facilitated diffusion ;
ref to active transport / use of ATP ;
36
Q

Explain why steroid hormones can diffuse through cell membranes.

A

fat soluble / non-polar / uncharged / hydrophobic ;

(so can move directly through) phospholipid bilayer ;

biology year 1 (15 decks)

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