biology topic 1 - cell biology Flashcards
(176 cards)
1
Q
all living things are made of what?
A
cells
2
Q
cells can be either what or what?
A
prokaryotic or eukaryotic
3
Q
what are eukaryote cells?
A
they are complex and include all animal and plant cells
4
Q
what are prokaryote cells?
A
they are smaller and simpler than eukaryotes
5
Q
eukaryotic organisms are made up of what?
A
eukaryote cells
6
Q
prokaryote is what?
A
a prokaryotic cell
7
Q
what does the nucleus do?
A
contains genetic material that controls the activities of the cell
8
Q
what does mitochondria do?
A
where most reactions for aerobic respiration happen
9
Q
what does cytoplasm do?
A
its a gel like substance where most chemical reactions take place. it contains enzymes
10
Q
what does the cell membrane do?
A
holds the cell together and controls what goes in and out
11
Q
what do ribosomes do?
A
where proteins are made in the cell
12
Q
what does a cell wall do?
A
it supports and strengthens the cell
13
Q
whats the cell wall made of?
A
cellulose
14
Q
what do chloroplasts do?
A
its where photosynthesis happens and where food is made for the plant
15
Q
what do chloroplasts contain?
A
chlorophyll
16
Q
what does chlorophyll absorb?
A
light needed for photsynthesis
17
Q
what does the vacuole contain?
A
cell sap
18
Q
if asked to work out the area of a subcellular structure what do you do?
A
work out the area of the shape its close to (rectangle)
19
Q
what is bacteria?
A
prokaryote
20
Q
what do bacterial cells have instead of a nucleus?
A
single circular strand of DNA that floats freely in the cytoplasm
21
Q
in a bacterial cell, what are the single rings of DNA called?
A
plasmids
22
Q
what don’t bacterial cells have?
A
chloroplasts or mitochondria
23
Q
does the cell wall go on the outside or the inside of the cell membrane?
A
outside
24
Q
what do microscopes let us see?
A
things we cant see with the naked eye
25
what do light microscopes use?
light and lenses
26
what do light microscopes let us see?
individual cells or large subcellular structures, like nuclei
27
what do electron microscopes use?
electrons
28
what do electron microscopes do better than light microscopes?
magnify an object and higher resolution
29
what can we see with electron microscopes ?
let us see smaller things in more detail( internal structures)
30
how do you calculate magnification?
image size/real size
31
how do you get from micrometres to mm?
divide by 1000
32
what do you do when calculating magnification if the number is very big or small?
put it in standard form
33
what is a slide?
a strip of clear glass
34
how do you prepare a slide?
put a drop of water on it
35
how do you prepare your onion to go onto the slide?
use tweezers to peel of the epidermal tissue from the onion skin
36
what do you add to the onion and water?
iodine so you can see the cell
37
what do you place on all water, onion skin, iodine?
a cover slip
38
whats the piece on a microscope you look into?
eyepiece
39
where do you put your slide on the microscope?
the stage
40
where is the light on a light microscope?
beneath the stage
41
what should your drawing be like of your magnified onion slide?
should take up at least half the space, no broken lines and should be drawn in proportion
42
what is differentiation?
the process by which a cell changes to become specialised for its job
43
cells that go through differentiation for mature animals are normally for what?
repairing or replacing cells
44
what is the function of a sperm?
to get the male DNA to the female DNA
45
how is it adapted to its function?
it has a long tail and a streamlined head to help it swim to the egg
46
what do sperm cells have a lot of?
mitochondria to give it the energy needed
47
what do sperm carry in its head to digest through the egg cell membrane?
enzymes
48
what is the function of a nerve cell?
to carry electrical impulses
49
how are nerve cells adapted to their function?
they are long with branched connection at their ends to connect to other nerve cells and form a network
50
what is the function of a muscle cell?
to contract quickly
51
how are muscle cells adapted to their function?
they are long and contain lots of mitochondria for contraction
52
what do root hair cells do?
absorb water and minerals
53
where do root hair cells grow?
on the surface of the plant roots
54
what does it give the plant with lots of root hair cells?
a large surface area for absorbing water and mineral ions from the soil
55
what are phloem and xylem cells specialised for?
transporting substances
56
what do phloem and xylem cells form?
phloem and xylem tubes which transport food and water around the plant
57
how are phloem and xylem tubes formed?
they are long and are joined end to end
58
what are the centre of xylem cells like?
hollow
59
what are the centre of phloem cells like?
very few subcellular structures so that stuff can flow through them
60
what are undifferentiated cells called?
stem cells
61
depending on what instructions they're given what can stem cells do?
they can differentiate into different types of cells
62
where are stem cells found in humans?
human embryos
63
why do stem cells excite scientists and doctors?
because they have the potential to turn into any cell at all
64
where are stem cells found in adults?
bone marrow
65
unlike embryonic stem cells what can adult stem cells only do?
turn into certain cell types, like blood
66
what can stem cells be used to grow in a lab?
clones
67
what does lots of medicine use to cure disease?
adult stem cells
68
what can stem cells from a healthy person do if transferred to a patient?
replace faulty blood cells
69
what can embryonic stem cells be used for?
to replace faulty cells in sick people
70
fro people with diabetes what could embryonic stem cells make?
insulin-producing cells
71
what can embryonic stem cells produce for a paralysed or spinal injury patient?
nerve cells
72
what can therapeutic cloning be used for?
to make stem cells with the same genetic makeup as the patient therefore the patients body wouldn't reject the cells
73
what are the risks of using stem cells in medicine?
stem cells grown in the lab may become contaminated with a virus which could make the patient sicker
74
why are some people against stem cell research?
because they believe that human embryos shouldn't be used for experiments as they are a potential human life
75
stem cell research is very controversial to the point where it is banned in some countries how is it allowed in the UK?
as long as it follows strict guidelines
76
where are stem cells found in plants?
the meristems
77
what can meristem stem cells produce?
clones of a whole plant quickly and cheaply
78
what can meristem cells also be used for ?
grow plants of rare species
79
what can meristem cells be used for regarding desired characteristics ?
they can grow crops of identical plants but with desired features eg disease resistant
80
what do cells in our body contain our genetic material in the form of ?
chromosomes
81
what do chromosomes contain?
genes that control the development of different characteristics
82
what do body cells normally have?
two copies of each chromosome - one from the father and one from the mother
83
how many pairs of chromosomes are their in a human cell?
23
84
when body cells in multicellular organisms divide to produce new cells whats it part of ?
the cell cycle
85
the stage of the cell cycle where the cell divides is called what?
mitosis
86
what do multicellular organisms use mitosis for?
to grow or replace cells that have been damaged
87
what does the end of the cell cycle result in?
in two new identical daughter cells
88
in a cell that's not dividing how is the DNA spread out?
in long strings
89
before a cell divides it has to grown and increase the mount of what?
subcellular structures
90
what happens in cell division after the subcellular structures duplicate?
the DNA duplicates ands forms X shaped chromosomes with identical arms
91
what happens in mitosis?
the chromosomes line up In the middle of the cell then cell fibres split them up. they move to the opposite ends and membranes form around the new chromosomes
92
what divides last in mitosis?
the cytoplasm and cell membrane
93
what is the product of mitosis?
two daughter cells with identical DNA to the parent cells
94
how do prokaryotes divide ?
binary fission
95
what happens in binary fission?
the circular DNA and plasmids replicate, the cell gets bigger and the DNA strands move to the opposite poles of the cell
96
what divides last in binary fission?
the cytoplasm divides and new cell walls form
97
what happens in binary fission after the cytoplasm divides?
two daughter cells are created
98
what are the daughter cells like in binary fission?
each daughter cell has one copy of the circular DNA but can have a varied number of plasmids
99
how often can bacteria replicate in the right conditions?
every 20 minutes
100
what happens to bacteria when they are In unfavourable conditions?
they stop dividing and die
101
how do you calculate the number of bacteria in a population?
total time bacteria is producing cells/ mean division time = number of divisions. then 2 to the power of number of divisions
102
what are bacteria grown on?
a culture medium
103
give an example of a culture medium?
agar jelly
104
how do you prepare an agar plate?
pour hot agar jelly into a petri dish and let the jelly cool/set
105
what is used to transfer microorganisms to the culture medium?
inoculating loop
106
what temperature shall cultures of microorganisms be kept at in school?
25 degrees
107
the temperature cultures of microorganisms are kept at in school is specific why?
if they are kept at over 25 degrees there is potential for pathogens to grow
108
in industrial conditions they are kept at a lot higher temperatures why?
so the culture will grow a lot faster
109
why does everything need to be sterilised when growing bacteria?
contamination of unwanted microorganisms will affect your results
110
what two things must be sterile before use?
the Petri dish and culture medium
111
how is the inoculating loop sterilised?
its passed over a burning flame
112
how is the lid of the petri dish put on after transferring the bacteria and why?
its lightly taped on to stop air microorganisms getting in
113
why are the petri dishes stored upside down?
to stop condensation falling onto the agar surface
114
when testing if antibiotics affect bacteria growth how do you do it?
place paper discs that are soaked in the antibiotic evenly spaced out and leaving space between them
115
what will the antibiotic do with the agar jelly?
diffuse ( soak into it)
116
what happens to antibiotic resistant bacteria?
it will continue to grow on the agar around the paper discs
117
what happens to antibiotic non resistant bacteria?
it will die
118
what's the clear area around the disc where the bacteria has died called?
the inhibition zone
119
what control variable is used and has to be used in this experiment?
a paper disc soaked in sterile water
120
why do you need a control disc?
to see the difference of what the antibiotic does
121
how long do you leave the plate with the antibiotic on for?
48 hours
122
the more effective the antibiotic is against the bacteria, the larger the what?
inhibition zone
123
how do you compare sizes of inhibition zones?
calculate the area of the inhibition zones
124
how do you find the area of the colony?
measure the diameter of the colony you want to find first
125
what is diffusion?
the spreading out of particles from an area of higher concentration to an area of lower concentration
126
what does diffusion happen in?
solutions and gases
127
what is a concentration gradient ?
the difference in concentration
128
the bigger the concentration gradient the what?
the faster the diffusion rate
129
how does a higher temperature give a faster diffusion rate?
the particles have more energy therefore they move around faster
130
only what can diffuse through cell membranes?
only very small molecules
131
what small molecules can diffuse through cell membranes?
oxygen, amino acids, glucose and water
132
what is osmosis?
the movement of water particles across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
133
what is a partially permeable membrane?
a membrane with very small holes in it so that only small molecules can pass through it
134
because there is more water molecules one side there is what?
a steady net flow of water into the region with fewer water molecules
135
how can you test osmosis?
cut identical cylinders of potato and put them in water and sugar solutions of high concentration
136
what do you measure first before putting the cylinders in the solution?
the mass of the potato cylinders
137
how long do you leave the potato in the solution?
for 24 hours or so
138
when you take the potato out what do you do?
dry the potato gently and measure the mass again
139
if water has been drawn in by osmosis, what will happen?
the mass will increase
140
if water has been drawn out by osmosis what will happen?
the mass will decrease
141
what is the dependant variable of this experiment?
chip mass
142
what is the independent variable of this experiment?
concentration of sugar solution
143
what happens in active transport?
when substances are absorbed from a lower to higher concentration ( goes against the concentration gradient)
144
how do root hairs take in minerals?
via active transport
145
what does active transport allow the plant to do?
absorb minerals from a dilute solution against the concentration gradient
146
what does active transport need that diffusion and osmosis dosent ?
needs energy from respiration
147
where does active transport happen in human?
taking glucose from the gut
148
what is active transport used in the gut for?
when there is a lower concentration of nutrients in the gut than there is blood
149
what normally happens in the gut and why?
diffusion as when theres a higher concentration of nutrients they naturally diffuse into the blood
150
therefore what does active transport allow ?
nutrients to be taken into the blood despite the fact that the concentration gradient is the wrong way
151
how easy it is for an organism to exchange substances with its environment depends on what ?
the organisms surface area to volume ratio
152
the larger the organism the what?
the smaller its surface area to volume ratio
153
how do you work out surface area to volume ratio?
work out the surface are of the object and then its volume
154
what does it tell us if the surface area to volume ratio of a mouse is 6:1?
it has a surface area 6 times its volume
155
why do dingle celled organisms only need direct diffusion?
because they have a large surface area compared to volume therefore its easy to exchange substances across the membrane
156
why do multicellular organisms need exchange surfaces?
because they have a smaller surface area compared to their volume - not enough substances can diffuse from the outside to supply their entire volume
157
how are exchange surfaces adapted regarding membranes?
they have a thin membrane, so there is a short diffusion distance
158
how are exchange surfaces adapted regarding surface area?
they have a large surface area so lots of substances can diffuse at once
159
how are exchange surfaces adapted regarding blood?
exchange surfaces in animals have lots of blood vessels to get stuff in and out of the blood quickly
160
how are exchange surfaces adapted regarding gas?
they are well ventilated so air can easily diffuse out
161
how does gas exchange happen in the lungs?
it diffuses oxygen into the blood and diffuses out the waste carbon dioxide
162
where does gas exchange happen in the lungs?
alveoli
163
how are alveoli adapted to gas exchange?
they have a large surface area, a moist lining, very thin walls and a good blood supply
164
in the small intestine what provides a really large surface area?
little projections called villi
165
why does the small intestine need a large surface area?
so that food is absorbed much more quickly into the blood
166
how is a leaf adapted to exchange surface regarding the underneath of the leaf?
it has little holes called stomata where the co2 diffuses in through
167
how is a leaf adapted to exchange surface regarding oxygen and water vapour?
they diffuse out through the stomata
168
how is a leaf adapted to exchange surface regarding the flattened shape of the leaf?
it increases the surface area of the exchange surface area
169
how is a leaf adapted to exchange surface regarding the air spaces in the leaf?
this also increases the surface area
170
what do gills have to be good at gas exchange?
a large surface area
171
what enters the gills via diffusion?
water containing oxygen which then diffuses from the water and oxygen foes into thr blood
172
what gives the gills a large surface area ?
thin plates called gill filaments
173
what do gill filaments have on them that increases the surface area even more?
lamellae (little tiny structures)
174
what does the lamellae have to speed up diffusion?
lots of blood capillaries
175
what maintains a large concentration gradient between the water and the blood ?
blood flows through the lamellae in one direction and water flows through the opposite direction
176
how does lots of diffusion happen from thw water into the blood?
because theres lots of oxygen in the water compared to the blood
