2.1.1 Cell Structure

Question 1

electron micrograph

Answer 1

photograph of an image seen using an electron microscope

Question 2

magnification

Answer 2

the number of times an image appears to be, compared to its actual size

Question 3

organelles

Answer 3

small structures within cells, each of which has a specific function

Question 4

photomicrograph

Answer 4

photograph of an image seen using an optical microscope

Question 5

resolution

Answer 5

the ability to distinguish between 2 spearate points in an image

Question 6

total magnification

Answer 6

magnifying power of the objective lens X magnifying power of the eyepiece lens

Question 7

magnification equation

Answer 7

image size/actual size

Question 8

eyepiece graticule

Answer 8

a measuring device
placed in the eyepiece of a microscope
acts as a ruler when you view an object under the microscope

Question 9

stage graticule

Answer 9

a precise measuring device
a small scale that is placed on a microscope stage
used to calibrate the value of eyepiece divisions at different magnifications

Question 10

double membrane bound

Answer 10

2 membranes

Question 11

advantages of staining specimen

Answer 11

increases contrast - easier to distinguish between organelles
stain binds to particular molecules
gram staining checks for bacteria and which bacteri

Question 12

wet mounting

Answer 12

putting a drop of water/stain onto the specimen

Question 13

dry mounting

Answer 13

observing specimen on a slide - assuming specimen is cut very thinly so light can pass through

Question 14

why is the refractive index of the medium the same as the glass

Answer 14

if light is refracted too much, image can become distorted

Question 15

why is a cover slip put on at an angle

Answer 15

avoids air bubbles - preventing the image from appearing distorted

Question 16

how does a SEM work in terms of electrons

Answer 16

electrons bounce off surface and are detected to produce an image

Question 17

how does a TEM work in terms of electrons

Answer 17

electrons pass through the specimen and are detected to produce an image

Question 18

magnification range of scanning electron microscope

Answer 18

100x - 100,000x

Question 19

magnification range of transmission electron microscope

Answer 19

100x - 2,000,000x

Question 20

adavantages of scanning electron microscope

Answer 20

observe 3D image
surface detail

Question 21

advantages of transmission electron microscope

Answer 21

high magnification
high resolution

Question 22

disadvantages of all electron microscopes

Answer 22

highly specialist training required
complex slide prep- image can become distorted
electron beam can damage specimen
specimen must be dead as images are viewed under a vacuum
cannot observe living processes

Question 23

success criteria for drawing

Answer 23

should occupy at least half of paper
single, clear, continuous lines
no shading
cells or tissues should be in correct proportions
label lines use pencil and ruler
labels written horizontally
do not use arrowheads
informative title
add a scale bar

Question 24

four organelles that make up the nucleus

Answer 24

nucleolus
nuclear pore
nuclear envelope
chromatin

Question 25

structure of nucleolus

Answer 25

contains ribosomal RNA (rRna)

Question 26

function of nucleolus

Answer 26

ribosome synthesis

Question 27

structure of nuclear pore

Answer 27

regular intervals around nuclear envelope

Question 28

function of nuclear pore

Answer 28

allows mRNA, tRNA, rRNA out of the nucleus

Question 29

structure of nuclear envelope

Answer 29

double membrane

Question 30

function of nuclear envelope

Answer 30

compartmentalises the nucleus

Question 31

structure of chromatin

Answer 31

loosely packed DNA

Question 32

function of chromatin

Answer 32

contains chromosomes

Question 33

structure of rough endoplasmic reticulum

Answer 33

covered in ribosomes
continuous with nuclear envelope
cisternae

Question 34

function of rough endoplasmic reticulum

Answer 34

protein synthesis at ribosomes
transport + folding of proteins

Question 35

structure of golgi apparatus

Answer 35

membranous sacs - cisternae
vesicles can be found on the sides

Question 36

function of golgi apparatus

Answer 36

packaging + modification of proteins into vesicles

Question 37

structure of chloroplasts

Answer 37

have two membranes separated by a fluid-filled space
inner membrane is folded = thylakoids
stack of thylakoids = granum

Question 38

function of chloroplasts

Answer 38

absorb light for photosynthesis

Question 39

structure of centrioles

Answer 39

“9+3” microtubule structure - made of tubulin
two centrioles at right angles to each other form a centrosome, which organises the spindle fibres during cell division

Question 40

function of centrioles

Answer 40

produces spindle fibres for cell division

Question 41

cellular functions of the cytoskeleton

Answer 41

mechanical strength to cells
cell support/stability
holding organelles in position
formation of cilia + flagella
cell movement, exocytosis, endocytosis, phagocytosis, cytokinesis

Question 42

ways in which the mitochondrial membrane is related to the functions of the mitochondria

Answer 42

contains electron carriers (the electron transport chain)
site of chemiosmosis, ATP synthesis, oxidative phosphorylation
allows the formation H+ gradient
outer membrane is highly permeable to allow movement of molecules