Topic 1- Cells Flashcards
(172 cards)
1
Q
what can organisms be?
A
prokaryotes or eukaryotes
2
Q
what are all living things made of
A
cells
3
Q
examples of prokaryotes
A
bacteria
4
Q
examples of eukaryotes
A
animal and plant cells
5
Q
what’s a eukaryote
A
an organism that is made up of a eukaryotic cell
6
Q
what’s a prokaryote
A
a prokaryotic cell (a single celled organism)
7
Q
what are the different parts of cells called
A
sub cellular structures
8
Q
what’s the nucleus?
A
contains genetic material that controls the activities of a cell
9
Q
what’s the cytoplasm
A
gel like substance where most of the chemical reactions happen
contains enzymes that control these chemical reactions
10
Q
what’s the cell membrane
A
holds the cell together and controls what goes in and out
11
Q
what’s the mitochondria
A
where most of the reactions for aerobic respiration happen
respiration transfers energy that the cell needs to work
12
Q
what are ribosomes
A
where proteins are made
13
Q
what do plant cells have
A
all the animal cell parts plus
rigid cell wall
permanent vacuole
chloroplasts
14
Q
what does an animal cell have
A
nucleus cytoplasm cell membrane mitochondria ribosomes
15
Q
what does a cell wall do
A
made of cellulose
supports the cell and strengthens it
16
Q
what’s the permanent vacuole
A
contains cell sap, a weak solution of sugar and salts
17
Q
what’s chloroplasts
A
where photosynthesis occurs, which makes food for the plant
contain chlorophyll which absorbs light for photosynthesis
18
Q
what type of cells are bacteria
A
prokaryotes
19
Q
what does a bacteria cell contain?
A
cytoplasm cell membrane cell wall strand of DNA that floats in the cytoplasm rings of DNA (plasmids)
20
Q
what don’t the bacteria cells have
A
chloroplasts or mitochondria or nucleus
21
Q
what’s differentiation
A
the process by which a cell changes to become specialised for its job
22
Q
What happens when the cells change
A
develop different sub cellular structures and turn into different types of cells which allows them to carry out specific functions
23
Q
When does most differentiation occur
A
as an organism develops
24
Q
What are the cells that differentiate in mature animals mainly used for
A
Repairing and replacing cells such as skin or blood cells
25
Give five specialised cells and what they’re specialised for
```
sperm- reproduction
nerve- rapid signaling
muscle- contraction
root hair- absorbing water and minerals
phloem and xylem- transporting substances
```
26
describe a sperm cells function
to get the male dna to the female dna
27
adaptations of a sperm cell
long tail
streamlined head to help swim to egg
lots of mitochondria to provide energy
enzymes in head to digest through the egg cell membrane
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function of nerve cell
To carry electrical signals from one part of the body to another
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adaptations with nerve cell
Long to cover more distance
branched connections at their end to connect to other nerve cells and form a network throughout the body
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Muscle cell function
contract quickly
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Adaptations of muscle cell
Long so they have space to contract
contain lots of mitochondria to generate the energy needed for contraction
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Root hair cell function
Cells on the surface of plant roots which grow into long hairs that stick out into the soil
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Adaptation of root hair cell
large surface area for absorbing water and mineral irons from the soil
thin walls to allow easy movement of water
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Function of phloem and xylem cells
they form phloem and xylem tubes which transport substances such as food and water around plants
to form the tubes the cells are long and joined end to end
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adaptations of phloem and xylem cells
Xylem cells are hollow in the centre and phloem cells have very few sub cellular structures so that stuff can flow through them
36
What do chromosomes contain
Genetic information
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What does the nucleus contain
Your genetic material in the form of cromosones
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What are chromosomes
coiled up lengths of DNA molecules
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What does each chromosome carry
A large number of genes
40
what do genes do
different genes control the development of different characteristics for example hair colour
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How many chromosomes does the body have
Two copies of each chromosome
one from the organisms mother and one from its father so humans have two copies of chromosomes one and two copies of chromosome two etc
23 pairs of chromosomes in total
42
What’s the stage of the cell cycle where the cell divides called
Mitosis
43
What’s the cell cycle
where body cells in multicellular organisms divide to produce new cells as part of a series of stages
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What does mitosis do
Grow or replace cells that have been damaged
45
describe the growth and DNA replication part of the cell cycle
1) in a cell thats not dividing the DNA is spread out in long strings
2) cell grows and increases the amount of sub cellular structures such as mitochondria and ribosomes
3) it’s duplicate the DNA so there is one copy for each new cell
the DNA is copied and forms X shaped chromosomes
each arm of the cromosome is an exact duplicate of the other
46
Describe the mitosis part of the cell cycle
1) the chromosomes line up at the centre of the cell and cell fibres pull them apart
the two arms of each chromosome go to opposite ends of the cell
2) membranes form around each of the sets of chromosomes
these become the nuclei of the two new cells
the nucleus has divided
3) The cytoplasm and cell membrane divides the new daughter cells are produced and contain exactly the same DNA
47
what’s binary fission
where prokaryotic cells can reproduce using a type of simple cell division called binary fission
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what happens in binary fission
the cell splits in two
49
describe the steps of binary fission
1) circular DNa and plasmids replicate
2) cell gets bigger and circular DnA strands move to the opposite ‘poles’ (ends of cell)
3) cytoplasm begins to divide and new cell walls begin to form
4) cytoplasm divides and two daughter cells are produced
5) each daughter cell has one copy of the circular DNA bit can have a variable number of copies of the plasmids
50
conditions for bacteria to divide?
warm
| lots of nutrients
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if conditions are unfavourable what happens to the cells
they stop dividing and eventually begin to die
52
what’s the mean division time
the average amount of time it takes for one bacterial cell to divide into two
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if you know the mean division time of a cell what can you work out?
how many times it has divided in a certain amount of time and so the number of cells it has produced in that time
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how do you find the mean number of divisions
divide total time that bacteria are producing cells by mean division time
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how do you find the number of cells
put 2 to the power of *how many divisions*
56
where is bacteria grown
in a culture medium
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what does a culture medium contain
carbohydrates
minerals
proteins
vitamins
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what can the culture medium be?
nutrient broth solution or solid agar jelly
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when bacteria is grown on agar plates what will it form?
visible colonies on the surface of the jelly or it will spread out to give an even covering of bacteria
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how do you make an agar plate
hot agar jelly is poured into shallow round plastic dishes called PETRI DISHES
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what’s an inoculating loop
inoculating loops transfer microorganisms to the culture medium
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what else can be used other than an inoculating loop
sterile dropping pippete and spreader
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what happens after inoculating loops transfer microorganisms
the microorganisms multiply
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why are microorganisms not kept higher than 25 degrees
because harmful pathogens are more likely to grow above this temp
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when are cultures incubated at high temps
industrial conditions
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how can you test the action of antibiotics or antiseptics in cultures of bacteria
1) place paper discs soaked in different concentrations/types of antibiotics on an agar plate that has an even covering of bacteria
LEAVE SPACE BETWEEN DISCS
2) antibiotic diffuses into jelly antibiotic-resistant bacteria will continue to grow around discs, but NON RESISTANT STRAINS WILL DIE
a clear area will be left where bacteria has died- inhibition zone
3) use a control, non antibiotic soaked disc (soaked in sterile water instead)
4) leave plate for 48 hours at 25 degrees
5) larger inhibition zone= more effective antibiotic
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whats a clear area will be left where bacteria has died called?
inhibition zone
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what can contamination do
result i. growth of pathogens
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to avoid uncontaminated cultures, you MUST?...
use sterilised petri dishes, by heating at high temps
pass inoculating loop through flame to kill unwanted microorganisms
lid of dish lightly taped on to stop microorganisms from air getting in
dish stored upside down to stop drops of condensation falling onto agar surface
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equation for area of inhibition zone
area= pi r squared
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what can the area equation be used for
area of colony
| size of inhibition zone
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what’s differentiation
the process by which a cell changes to become specialised for its job
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what type of cells are stem cells
undifferentiated
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what can stem cells do
divide to produce lots more undifferentiated cells
they can differentiate into different types of cells depending on what instructions they’re given
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where are stem cells found
early human embryos
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what do stem cells have the potential to do
turn into any kind of cell at all
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where are adult stem cells found
bone marrow
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what can bone marrow stem cells do
turn into only certain types of cells such as blood cells
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what can all stem cells be used for
they can be grown in the lab to produce clones
made to differentiate into specialised cells to use in medicine or research
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what can stem cells do to cure disease
bone marrow- replace faulty blood cells
embryonic- insulin producing cells, nerve cells
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what’s therapeutic cloning
where an embryo could be made to have the same genetic information as the patient
this means that some cells produced from it would also contain the same genes and so wouldn’t be rejected by patient’s body if used to replace faulty cells
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stem cell risks
becoming contaminated with virus which could be passed on to patient
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arguments against and for stem cells
-Potential human life
+curing existing patients who are suffering is more important than the rights of embryos
+embryos used are unwonted ones which would probably just be destroyed
-scientist should find other sources of stem cells
84
In some countries stem cell research is...
BANNED
85
Where arestem cells found in plants
meristems
86
what happens to cells in the meristem tissues
They can differentiate into any type of plant cell
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Plant stem cells can be used to produce what
clones of plants (rare species and disease resistant)
88
what’s diffusion
the spreading out of particles from an area of higher concentration to an area of lower concentration
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where does diffusion happen
in solutions and gases because the particles in these are free to move about randomly
90
whats the conc gradient
the difference in concentration
91
the bigger the conc gradient...
the faster the diffusion rate
92
the higher the temp...
the faster the diffusuion rate because particles will have more energy
93
what sort of substances move in and out of cells by diffusuion
dissolved
94
what does the cell membrane do in diffusion
let stuff in and out
95
what molecules can diffuse through cell membranes
small molecules such as oxygen, glucose, amino acids and water
96
what molecules can't fit through the membrane
starch and proteins
97
if there are a lot more particles on one side of the membrane...
theres a net (overall) movement from that side
98
the larger the surface area of the membrane...
the faster the diffusion rate because more particles can pass through at once
99
what is osmosis
the movement of water particles across a partially permeable membrane from a region of higher water concentration to an region of lower water concentration
100
whats a partially permeable membrane
a membrane with very small holes in it, so only water can pass through, beacause the molecules are very small
101
what way do water molecules travel through the membrane
randomly, both ways
102
whats the net flow of osmosis
where because there are more water molecules on one side than on the other, theres a steady flow of water into the region with fewer water molecules (the stronger sugar solution). this means the water gets more dilute
103
what is the water trying to do in osmosis
dilute the strong sugar solution and even up the conc on each side of the membrane
104
describe the potato practical
1) cut up potato evenly
2) put each one in beakers with different sugar solutions
3) one should be pure water, then 1 mol/dm3, 0.2 mol/dm3, 0.4mol/dm3 etc
4) measure mass of each potato cylinder
5) leave potato in sugar solutions for 24hours or so
6) dry the cylinders and measure mass agai
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if the cylinders of potato have increased mass...
they have drawn in water by osmosis
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if the cylinders of potato have increased mass...
they have drawn out water by osmosis
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dependent variable of potato experiment
chip mass
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independent variable of potato experiment
conc of sugar solution
109
control variables of potato experiment
volume of solution, temp, time, type of sugar etc
110
potential errors in potato experiment
excess water gives higher mass- not fully dried cylinders of potato
conc of sugar changes-water evaporates from beakers
111
whats active transport
where substances are absorbed against a conc gradient, from lower to higher conc, using energy
112
what do root hair cells take in
minerals and water
113
what are the branches of roots covered in
microscopic hairs
114
what do microscopic hairs do to the plant
give them a large surface area for absorbing water and mineral ions from the soil
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what do plants need minerals for
healthy growth
116
the conc of minerals is higher in the root hair cells than...
the soil around them , so diffusion cant be used to take up minerals from the soil
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what does active transport allow plants to do
absorb minerals from a very dilute solution, against the conc gradient
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what does active transport need to work
energy
119
where else does active transport happen
in the gut when there is a lower conc of nutrients in the gut but a higher conc of nutrients in the blood
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when else does active transport happen in humans
when glucose can be taken into the bloodstream when its conc in the blood is already higher than in the gut. It can then be transported to cells, where it is used for respiration
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organisms exchange substances with their...
environment
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what do cells use to take in substances that they need and to get rid of waste products
diffusion
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the larger an organism is, the smaller the...
SA is compared to its volume
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SA equation
length x width
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volume equation
length x width x height
126
to simplify the ratio, what do you do
divide both sides of the ratio by the volume
127
whats the sa: v ratio like in single celled organisms
large sa compared to their volumbe,
so gases and dissolved substances can diffuse directly into or out of the cell across the cell membrane
enough substances can be exchanged across the membrane to supply the volume of the cell
128
whats the sa: v ratio like in multicellular organisms
small sa compared to volume, so not enough substances can diffuse from their outside surface to supply their entire volume. This means they need an exchange surface to allow enough of the necessary substances to pass through
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how are exchange surfaces adapted to maximise effectiveness
thin membrane- substances only have short distance to diffuse
large SA- lots of substances can diffuse at once
in animals, have lots of blood vessels- to get stuff in and out of body quickly
gas exchange surfaces in animals (eg.alveoli) are ventilated- are moves in and out
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what is the job of the lungs
to transfer oxygen to the blood and remove waste carbon dioxide from it
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what are the alveoli specialised for
to maximise the diffusion of O2 and CO2
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adaptations of alveoli
enormous SA
moist lining- dissolving gases
Thin walls
good blood supply
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where are the villi?
the inside of the small intestine
134
what do villi do?
they increase the SA in a big way so that digested food is absorbed much more quickly into the blood
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what do villi have
a single layer of surface cells
| a very good blood supply to assist quick absorption
136
The top and bottom of the leaf are covered with what
a layer of very thin cells called epidermal cells and they form epidermal tissue
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Epidermis adaptations
* At the top of the leaf are the upper epidermis and at the bottom are the lower epidermis
* The epidermis protects the surface of the leaf
* The upper epidermis is transparent and allows light to pass through to the photosynthetic cells below
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Waxy cuticle
* The upper epidermis is covered with a thin layer of oily material called the waxy cuticle
* The waxy cuticle reduces the evaporation of water form the leaf and helps it from drying out
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Stomata
* Allow carbon dioxide to enter the leaf and oxygen to leave
* Help control the amount of water vapour that can pass out of the leaf
* On either side, there are guard cells
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Palisade mesophyll has what?
palisade cells
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what do palisade cells have lots of
chloroplasts
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chlorophyll does what
which absorbs the light energy needed for photosynthesis
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The spongy mesophyll is full of what
air spaces
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what do air spaces in spongy mesophyll allow
carbon dioxide to diffuse from the stomata through the spongy mesophyll to the palisade cells
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what diffuses from the palisade cells through the spongy mesophyll to the stomata
oxygen and water vapour
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what does xylem tissue do
transports water from the roots to the stem and leaves
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what else does the xylem do
xylem also transports dissolved minerals ions. These include magnesium which is used to make chlorophyll
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what does the phloem do
• Transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant
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what are sugars transported by phloem used for?
sugars can be used immediately, for example glucose and respiration. Or they can be stored, for example starch.
150
translocation definition?
• The movement of sugars and other molecules through phloem tissue
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wheres meristem tissue found
growing tips eg shoots and roots
152
what does meristem tissue contain
• Contains stem cells, which can differentiate into different types of plant tissue
153
whats the underneath of the leaf
an exchange surface
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what diffuses into the leaf then into the cells for photosynthesis?
CO2
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what does CO2 use to diffuse in
stomata
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wheres water vapour lost from in the leaf
stomata
157
what do guard cells do
close the stomata if the plant is losing too much water
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what does the flattened shape of the leaf do
it means the area of the exchange ssuface is increased so its more effective
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whats another exchange surface in the leaves formed by
walls of the leaf cells
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what do the walls of the cells inside the leaf do
the air spaces inside the leaf increase the area of the surface so more chance for CO2 to get into the cells
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where does water evaporate from the leaf
the cells
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by what process does water vapour leave the leaf
diffusion, theres more inside the leaf than there is outside the leaf
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whats the gas exchange surface in a fish
gills
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how does water enter and exit the fish
enters through mouth
| exits through gills
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what happens to oxygen and CO2 in the fish
oxygen diffuses from water -> blood in gills
| CO2 diffuses from the blood -> water
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what are gills made of
gill filaments, which make a big surface area for exchange of gases
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what are gill filaments covered in
lots of tiny structures called lamellae, increasing the SA
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the lamelllae have lots of what?
lots of blood capilaries to speed up diffusion
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what do the fish cells have to minimise the distance gas has to difuse?
thin surface layer
170
how is a large conc gradient maintained between water and blood in fish
blood flows through lamellae in one direction and water flows over in the opposite direction
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describe the conc of oxygen in water (fish)
its always higher than the blood, so as much oxygen as possible diffuses from the water in the blood
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formula for magnification
magnification = image size divided by real size
