B1 - Cell Structure & Transport Flashcards
(59 cards)
1
Q
What is a eukaryotic cell?
A
- a plant or animal cell with cell membrane, cytoplasm
- genetic material enclosed in nucleus
- organelles
2
Q
What is a prokaryotic cell?
A
- genetic material is not enclosed in nucleus
- no organelles
- DNA found as a loop
- one or more plasmids
- cytoplasm surrounded by cell wall
3
Q
What is the difference between the two?
A
- genetic material
- prokaryotic is smaller
4
Q
What is a plasmid?
A
- a small ring of DNA
5
Q
What parts does an animal cell have?
A
- nucleus, cell membrane, cytoplasm, mitochondria and ribosomes
6
Q
What parts does a plant cell have?
A
- nucleus, cell membrane, cytoplasm, mitochondria, ribosomes
- chloroplasts, cell wall and vacuole
7
Q
Function of the nucleus?
A
control the cell
8
Q
Function of the cytoplasm?
A
site of chemical reactions, has enzymes
9
Q
Function of the cell membrane?
A
controls what enters and leaves the cell
10
Q
Function of the mitochondria?
A
site of respiration - energy for survival and function
11
Q
Function of ribosomes?
A
site of protein synthesis
12
Q
Function of chloroplasts?
A
site of photosynthesis, make glucose
13
Q
Function of permanent vacuole?
A
supports the cell and contains cell sap
14
Q
How is the cell wall strengthened?
A
cellulose
15
Q
Prefixes for centi, milli, micro and nano?
A
Centi – 10-2
Milli – 10-3
Micro – 10-6
Nano – 10-9
16
Q
How is a sperm cell adapted for its function?
A
- streamlined shape
- tail to swim to ovum
- nucleus has 1 set of chromosomes
- lots of mitochondria from respiration to release energy
- to carry father’s genetic information + fertilise the egg
17
Q
How is a red blood cell adapted for its function?
A
- no nucleus so more room for oxygen
- haemoglobin binds to oxygen molecules
- flat biconcave shape to increase surface area
- to transport oxygen around the body
18
Q
How is a nerve cell adapted for its function?
A
- Long axon – move impulses in the body
- Dendrites – contact other nerves at synapses
- Mitochondria – energy to make neurotransmitters
- Myelin sheath – provides insulation
- to carry electrical impulses around the body
19
Q
How is a muscle cell adapted for its function?
A
- ## to contract and relax to allow movement
20
Q
How is a root hair cell adapted for its function?
A
- increased surface area for more water
- permanent vacuole - increased speed of osmosis
- mitochondria - energy for active transport of minerals
- to absorb water and mineral ions from soil
21
Q
How is a xylem cell adapted for its function?
A
- few cell structures - they are dead for more space
- supported by lignin
- no nucleus, cytoplasm so water + minerals can flow easily
- to transport water around the plant
22
Q
How is a phloem cell adapted for its function?
A
- few cell structures
- supported by companion cells - contain mitochondria for energy transfer and moving food through phloem
- to transport sugars around the plant
23
Q
What is cell differentiation? (2)
A
- the process by which unspecialised cells develop/change into their mature forms
- it acquires different sub-cellular structures to enable it to carry out a certain function
24
Q
Examples of specialised cells?
A
- stem cells
25
When do animal cells differentiate?
-Most types of animal cell differentiate at an early stage.
26
When do plant cells differentiate?
- Many types of plant cells retain the ability to differentiate throughout life.
27
What are the advantages of using an electron microscope?
- higher resolution and magnification
- can be used to examine a cell in finer detail and has led to a better understanding of sub-cellular structures
28
REQUIRED PRACTICAL 1:
How do you prepare a slide?
1) add a drop of water to the microscope slide
2) place a thin layer of tissue on slide
3) stain tissue with drops of iodine solution
4) place coverslip on top
29
REQUIRED PRACTICAL 1:
How do you observe a slide?
1) place slide on stage and use lowest power objective lens
2) turn course focus wheel to bring image into focus
3) increase the power of objective lens to increase magnification
4) turn fine focus wheel to bring the image into clearer focus
30
What is the formula for magnification?
Magnification=image size/actual size
(IAM)
31
What is magnification?
size of an image compared to its actual size
32
What is resolution?
The ability to tell the difference between two points
33
What is binary fission?
- Asexual cell division used by prokaryotic cells to reproduce and split into two
- As often as once every 20 minutes if they have enough nutrients and a suitable temperature.
34
What happens during binary fission?
1. Plasmids and DNA are copied
2. Cell gets bigger and DNA strands move to opposite sides of the cell
3. Cytoplasm of each cell splits & new cell walls form
4. Daughter cells are formed
5. For some bacteria, this occurs every 20 minutes
35
What conditions do bacteria need for binary fission?
- warm environment
- lots of nutrients
36
What is the formula for calculating the number of bacteria in a given time?
2^n
n=number of rounds of division in the time given in minutes
eg. bacteria divides every 20 mins. Calculate the number of bacteria present after 3 hours.
3 hours = 180 minutes
180/20 = 9 rounds of division
2^9 = 512 bacteria present
ANSWER NEEDS TO BE IN STANDARD FORM:
512 = 5.12 x 10^2
37
REQUIRED PRACTICAL 2:
How do you make an agar plate and what is it used for?
1) Agar jellies are prepared in petri dishes to form plates
2) Microorganisms are spread on the plates
3) Keep the plates at below 25C0 - minimise the risk of harmful pathogens growing
38
REQUIRED PRACTICAL 2:
investigating disinfectants + antibiotics
1) sterilise agar and Petri dish before use, disinfect the bench
2) pass inoculating loop through flame of bunsen burner
3) remove lid of the Petri dish and bottle containing bacteria
4) use inoculating loop to remove bacteria from the bottle
5) spread bacteria over agar and replace lid as quick as possible
6) put lid on the petri dish and secure lid with tape, incubate at 25 degrees for 24 hours
39
REQUIRED PRACTICAL 2:
what measurement do you need to take to calculate the clear area of no bacterial growth?
the radius of the clear area
40
REQUIRED PRACTICAL 2:
How would you sterilise equipment before use?
heat over 100 degrees
41
REQUIRED PRACTICAL 2:
What precautions can you use to avoid contamination?
sterilise, work near a flame, pass inoculating loop through flame, minimise opening of containers
42
REQUIRED PRACTICAL 2:
Why should the petri dish be stored upside down?
prevent condensation falling on agar plate and disrupting growth of microbes
43
REQUIRED PRACTICAL 2:
Why should a control disk be used when testing different chemicals?
comparison to compare effect of not using a chemical at all
44
What is diffusion?
- Spreading out of particles net movement from high to low concentration
45
What factors affect the rate of diffusion?
- concentration - increased concentration gradient=increased rate
- temperature - increased temp=increased rate(more kinetic energy)
- surface area - increased=increased rate
46
How does surface area:volume ratio affect the rate of diffusion?
When the cell increases in size, the volume increases faster than the surface area, because volume is cubed where surface area is squared.
47
How is the small intestine adapted for diffusion?
- has villi for large surface area
- cell membranes are thing for short diffusion pathway
- rich blood supply for steep concentration gradient
48
How are the lungs adapted for diffusion?
- lots of alveoli for large surface area
- thin membrane for short diffusion pathway
- good ventilation
- good blood supply for steep concentration gradient
49
How are gills in a fish adapted for exchange?
- large surface area
- thin membrane for short diffusion pathway
- good ventilation + blood supply
50
What happens during diffusion in a fish?
- oxygen from water into blood in the gill filaments
- carbon dioxide from gill filaments into water
51
What happens during diffusion in plants?
- CO2 for photosynthesis comes into leaves through stomata
- O2 during photosynthesis comes out of leaves through stomata
52
What is osmosis?
- diffusion of water from dilute solution to concentrated solution through a partially permeable membrane
53
REQUIRED PRACTICAL 3:
effects of osmosis on plant tissue
1) cut tubes of potato using a cork borer
2) trim potato cylinder so it is at a controlled length
3) record the mass of the potato cylinder
4) put cylinder in a boiling tube of solution and leave for a fixed period of time
5) remove the cylinder and blot dry
6) record the mass of the potato cylinder
7) measure and record new length
8) repeat twice to calculate average
9) repeat for other concentrations
10) calculate percentage change in mass
54
How do you calculate percentage change in mass?
calculate percentage change:
change in value/original value x 100
55
REQUIRED PRACTICAL 3:
When would a potato piece left in solution increase In mass?
Solution would be more dilute than potato so water enters through osmosis
56
REQUIRED PRACTICAL 3:
When would a potato piece left in solution decrease in mass?
Solution would be more concentrated than potato so water leaves potato through osmosis
57
What is active transport?
- movement of particles from a dilute solution to a more concentrated solution
- low to high (against concentration gradient)
- energy used from respiration
58
Example of active transport in animals?
- Sugar to be transferred from a low concentration in the gut to a higher concentration in the blood
- Glucose from the gut to be absorbed, used for respiration
59
Example of active transport in root hair cell?
- Root hair cells transport ions like magnesium into the plant from soil
- concentration of ions in the soil is lower than in the root hair cell, so active transport is used
- ions are moved into the xylem to be transported to the leaves
