1 - cell bio whole of topic Flashcards
1
Q
light microscope
A
- use light and lenses to form image of subject and magnify it
- see large subcellular structures like nucleui
- easier to transport than an electron microscope
2
Q
electron microscope
A
- use electrons instead of light to form image
- higher mag and higher resolution than light microscope
3
Q
formula for magnification
A
mag = image/actual
4
Q
how do you prep a slide in microscopy
A
- a drop of water to middle of slide
- cut onion an separate into layers - use tweezers to peel of epidermal tissue from bottom of one layer
- put this tissue on water on the slie
- rop iodine solution on it to stain it
- put cover slip on top - sie ways so no air bubbles
5
Q
how to use a light microscope
A
- clip slide onto stage
- select lowest objective lens
- use coarse adjustment knob and move stage up below objective lense
- look down eyepiece and use fine adjustment knob to get in focus
6
Q
whats differentiation
A
a cell changes to become specialise for its job
7
Q
specialised sperm cell
A
- specialised for reproduction
- long tail + stream lined to swim to egg
- lots of mitochonria to give it enegrry
- enzyme in its hea - digest through egg
8
Q
specialised nerve cell
A
- specialised for carrying electrical signals from one part of the boy to the other
- long
- cranched connections to reach further
9
Q
specialised muscle cell
A
- specialised for muscle contraction
- long
- lots of mitochondria to get energy
10
Q
specialised root hair cell
A
- specialised for absorbing water and minerals
- hairs
- larger sa for absorption
11
Q
why do we need to the cell cycle
A
for growth, development and repair
12
Q
2 main stages in the cell cycle
A
- growth and DNA replication
- mitosis
13
Q
stage one of cell cycle - growth and DNA replication
A
- DNA spread into long strings
- increases the amount of sub-cellular structures
- duplicates its DNA - one copy for each new cell - each arm is an exact duplicate of the other
14
Q
stage two of the cell cycle - mitosis
A
once duplicated = ready for mitosis
1. chromosome line up in the centre
2. cell fibre pull them apart which go to opposite ends of the cell
3. membranes form around each of these sets of chromosomes which become the nuclei of the 2 new cells
4. lastly the cytoplasm and cell membrane divide
==== 2 identical daughter cells who are clones of their parent
15
Q
whats binary fission
A
when a prokaryotic cell wants to reprouce
16
Q
process of binary fission
A
- stand of DNA an plasmids replicate
- cell gets bigger an strands of DNA move to opposite poles of cell
- cytoplasm divides and new cell wall forms
- daughter cells are produced - each has one copy of na but a variety amount of plasmids
17
Q
whats bacteria like as it divies
A
it can divide very fast in favourable conditions
18
Q
growing bacteria - practical
A
- hot agar jelly poured into shallow round Petri dishes
- once its cooled wire loops transfer micro-organisms to the culture medium
- sterile dropping pipette can be used to get an even covering of bacteria so that the microorganisms can then multiply
19
Q
how do you find the effect of antibiotics on bacterial growth - practical
A
- place paper discs soaked in different concentrations of antibiotics on agar plate that has an even covering of bacteria
- antibiotics will diffuse onto agar jelly
- a clear area will be left where the non-resistant trains have died - INHIBITION ZONE
- you need a control disc that hasn’t be soaked bc then you can see the effect of antibiotics alone
- leave plate for 48 hours at 25 degrees
- the more effective antibiotic the larger the inhibition zone will be
20
Q
how to use uncontaminated culture in petri dish practical
A
- petri dish sterilise -by heating etc - kill any unwanted microorganisms
- sterilise wire loop over bensen burner
- lightly tap on lip - stop microorganisms from the air getting in
- petri dish stored upside to stop condensation falling onto agar surface
21
Q
what are stem cells
A
- undifferentiated cells
- can be used in a lab to produce clones
22
Q
different types of stem cells
A
- embryonic stem cells - found in embryos - can differentiate into ANYTHING
- adult stem cells - found in bone marrow - CANT differentiate into anything
23
Q
stem cells - curing diseases
A
- transfer healthy adult stem cells to an unhealthy person - replace the faulty blood cells
- embryonic can make insulin - producing cells and help ppl with diabetes
- therapeutic cloning - produces an embryo with genes that are identical to the patient’s
24
Q
why are people against stem cells in research
A
- human embryos shouldn’t be an experiment bc they have potential for human life
- curing existing patients who are suffering is more important than the rights of embryos
- embryos in research are usually unwanted and normally would j get destoryed
- campaigns for other sources of stem cells - not embryos
25
plant stems cells - where, what, uses
- found in the meristems
- can differentiate into anything at any point in life
- used to: produce clones fast and cheap // grow more rare species // growth loads of desirable plants eg disease resistant
26
diffusion definition
spreading out of particles from a high to a low concentration
27
osmosis definition
movement of water molecules across a partially permeable membrane from high water concentration to low water concentration
28
how do root hair cells use active transport
- active transport allows the root hair cells to absorb minerals from a v dilute solution against the concentration gradient
- this is essential to growth but needs energy from respiration to work
29
how does the human body use active transport
- lower conc of nutrients in gut and higher in blood
- active transport allows the nutrients to be taken into the blood from the gut even though the blood alreay has a higher concentration
30
whats the SA : V ratio depending on the size of the organism?
the larger the organism, the smaller its surface area is compared to its volume
31
single-celled organisms compared to multicellular organisms which exchange surfaces
1. SINGLE CELLED - substances diffuse DIRECTLY in or out the cell because of their LARGE SA compared to their volume
2. MULTICELLULAR - smaller SA compared to volume so not enough substances can be exchanged
32
adaptations of exchange surface to maximise effectivness
- thin membrane = short distance to diffuse
- large SA lots can diffuse through at once
- lots of blood vessels (in animals) to go in and out blood fast
33
how are the alveoli specialised to maximise iffusion
- HUGE sa
- moist lining
- thin walls
- good blood supply
34
gas exchange in the lungs
1. job of lungs is to transfer oxygen from blood and remove waste carbon dioxide from it
2. lungs contain millions of air sacks called alveoli where gas exchange takes place
35
how are the villi adapted
- small intestine covered in millions of villi
- Increase SA so food is absorbed faster into blood
- goo blood supply
36
how are leaves adapted for gas exchange
1. stomata
- carbon dioxide diffuses in an oxygen&water vapour diffuse out
- size of stomata is controlled by guard cells which close if leaf is losing too much water
2. leaf has a flat shape
- increases the area of the exchange surface
37
how are gills on fish adapted for gas exchange
- water enters fish through mouth and passes out through gills
- as this happens - oxygen diffuses from water into the blood in the gills and co2 diffuses from the blood into the water
- each gill made up of filaments - large SA for gas exchange
- lots of blood capillaries - speed up diffusion rate
-
38
convesion units
nm
divide by 1000
um
divide by 1000
mm
divide by 1000
m
divide by 1000
km
39
why does binary fission occur
for prokaryotic cells to reproduce
