Cell Biology Flashcards
1
Q
What structures do all eukaryotic cells (plant & animal) have?
A
-Cell membrane, cytoplasm, and genetic material enclosed in a nucleus.
2
Q
What parts are found in most animal cells and plant cells?
A
- Nucleus, cytoplasm, cell membrane, mitochondria, and ribosomes.
3
Q
What additional parts are found in plant cells?
A
-Chloroplasts, a permanent vacuole with cell sap, and a cell wall made of cellulose.
4
Q
How is an electron microscope better than a light microscope?
A
- It has higher magnification and resolution, allowing finer detail of sub-cellular structures.
5
Q
What is cell differentiation?
A
-The process where a cell develops new sub-cellular structures to perform a specific function.
6
Q
When do most animal cells differentiate?
A
- At an early stage of development.
7
Q
Can plant cells differentiate throughout life?
A
-Yes, many types of plant cells can.
8
Q
What is the magnification formula?
A
- Magnification = Size of image ÷ Size of real object
9
Q
How do bacteria multiply?
A
- By binary fission, often every 20 minutes in suitable conditions.
10
Q
How can bacteria be grown in labs?
A
- In nutrient broth or on agar gel plates.
11
Q
Why are uncontaminated cultures important?
A
- To accurately test disinfectants and antibiotics.
12
Q
What happens before a cell divides?
A
-It grows, increases sub-cellular structures, and DNA replicates.
13
Q
What is mitosis?
A
-A process where chromosomes are separated into two nuclei, forming two identical cells.
14
Q
Why is mitosis important?
A
-for the growth, repair, and replacement in multicellular organisms.
15
Q
What is a stem cell?
A
-An undifferentiated cell that can form many types of cells.
16
Q
Where can stem cells be found?
A
-In human embryos, adult bone marrow, and meristem tissue in plants.
17
Q
Where can stem cells be found?
A
-In human embryos, adult bone marrow, and meristem tissue in plants.
18
Q
What is therapeutic cloning?
A
-Creating an embryo with the same genes as a patient for medical treatment.
19
Q
What are the potential risks of stem cell use?
A
- Viral infection and ethical or religious concerns.
20
Q
How are plant stem cells used?
A
-to clone plants
-protect rare species
-produce crops with useful traits.
21
Q
What is diffusion?
A
-the net movement of particles from an area of low concentration to an area of high concentration
22
Q
What affects diffusion rate?
A
-Concentration gradient
-temperature
-membrane surface area.
23
Q
What is osmosis?
A
-Diffusion of water through a partially permeable membrane from dilute to concentrated solution.
24
Q
What is active transport?
A
-Movement of substances against a concentration gradient, using energy from respiration.
25
Where is active transport used?
-Root hair cells absorb minerals, and sugar is absorbed from the gut into the blood.
26
How is the effectiveness of exchange surfaces increased?
- Large surface area,
-thin membrane
- good blood supply (in animals), and ventilation (for gases).
27
Why is surface area to volume ratio important?
- A large ratio allows single-celled organisms to exchange substances effectively.
28
what is a cell?
-the smallest unit of life that can live on its own
-cells make up all living organisms and their tissues
29
what are the differences between eukaryotic cells and prokaryotic cells?
-eukaryotic cells are much larger than prokaryotic cells
-eukaryotic cells contain membrane-bound organelles while prokaryotic cells do not
-eukaryotic cells keep their DNA in the form of chromosomes within a nucleus, whilst prokaryotic cells have their DNA loose in the cell
30
for animal, plant, and bacterial cells state whether they are either eukaryotic or prokaryotic
-animal and plant cells are eukaryotic
-bacterial cells are prokaryotic
31
what is the cell membrane and what is its role?
-the cell membrane is a protective barrier around the outside of the cell
-it controls which substances can pass in and out of the cell.
32
what is the cytoplasm and what is its role?
-the cytoplasm is a jelly-like liquid that fills the cell
-allows substances to dissolve and it is where chemical reactions take place
33
what is the role of the nucleus?
-it contains the genetic material ( DNA) of the cell .
34
what is the role of the mitochondria?
-they carry out aerobic respiration and so provide energy for the cell to use in chemical reactions
35
what is the role of the ribosomes?
-they are the site of protein synthesis
36
what is the role of the plant cell wall?
-it provides strength and structure to the plant cell wall, preventing it from bursting or shrinking when water enters/leaves the cell via osmosis
37
what does the permanent vacuole contain?
-cell sap ( a solution of salts, sugars and amino acids)
38
what is the role of the permanent vacuole?
-it supports the wall, maintaining its turgidity
39
what is the role of chloroplasts?
-chloroplasts are the site of photosynthesis and so make glucose for the cell
40
what is chlorophyll?
-a green pigment within chloroplasts that absorb sunlight for photosynthesis
41
name 7 sub-cellular structures ( organelles) found in bacterial cells
-cell wall
-cell membrane
-cytoplasm
-circular strand of DNA
-plasmid
-ribosome
-flagellum
42
what are plasmids and what are their role?
-small, circular loops of DNA that are separate to the main DNA
-they contain 'extra genes' that are sometimes useful to the bacteria, such as antibiotic resistance
43
what is the prokaryotic cell wall composed of?
-peptidoglycan
44
what is the definition of magnification?
-how many times larger an image appears compared to the real object
45
what is the role of the microscope?
-to magnify small objects so they appear larger
46
define resolution
-the smallest distance between two objects that can be distinguished
47
how does a light microscope work?
-light from a mirror passes through the specimen, objective lens, the eyepiece lens and into your eye
-the two lenses magnify the image and cause the image to be much larger than the real object
48
what are two types of microscopes?
-light microscopes
-electron microscopes
49
what is the magnifying power of a light microscope?
-x2000
50
give 5 advantages of light microscopes compared to electron microscopes
-cheap
-easy to use
-small so easy to transport
-produce colour images
-can see living specimens
51
explain the main disadvantage of light microscopes
-light microscopes rely on light whereas electron microscopes rely on electrons
-light has a much longer wavelength then electrons, which means that light microscopes have a lower resolution than electron microscopes
-this means light microscopes have a lower magnification and so can't see many details within cells such as the details of sub-cellular structures.
52
what is the magnifying power of an electron microscope?
-2,000,000
53
what is the main advantage of electron microscopes?
-electron microscopes have a greater resolution and magnification
-they can be used to see details within sub-cellular structures
54
why do electron microscopes have a greater magnification and resolution than light microscopes?
-they use a beam of electrons rather than light waves, and the electrons have a shorter wavelength than light waves.
55
give 5 disadvantages of electron microscopes
-expensive
-large so difficult to transport
-difficult to use so require specialist training
-can only view dead specimen
-images are generated in black and white
56
rearrange the units of distance below from smallest to largest:
m,mm μm
-nm,μm,mm,cm, m, km
57
how do you convert mm to m
-divide by a thousand
58
how do you convert micrometers (μm) to metres (m) .
- divide by a million
59
how do you convert nanometres ( nm) to metres?
-divide by a billion
60
how many mm are there in 1 cm?
-10 mm in 1 cm
61
how many nm are there in 1 μm
-1000 nm in 1 μm
62
give 3 reasons why multicellular organisms need a continuous supply of new cells
-growth
-development
-repair
63
what is the cell cycle?
-the series of steps that take place as a cell grows and then divides
64
where in the body does mitosis take place?
-everywhere
65
how many cells does mitosis produce?
-produces 2 cells
66
what are cells produced by mitosis called?
-daughter cells
67
are cells produced by mitosis genetically identical or genetically uniquie?
-genetically identical
68
what is binary fission?
-the process by which bacteria divide and reproduce
69
which two things must a bacterial cell do before it can divide?
-grow
-replicate its genetic material
70
describe the steps of binary fission
-the bacteria grows and reproduces its genetic material
-the two circular strands of DNA move to opposite sides of the cell
-a new cell wall forms down the middle of the cell
-the two halves pull apart to form two cells
71
during binary fission, is the genetic material split equally between the two new cells?
-each cell will always receive one copy of the circular strands of DNA, however, the plasmids are randomly arranged so there are often more plasmids in one cell then the other
72
which three conditions do bacteria require for fast growth?
-warmth
-moisture
-plenty of nutrients
73
in binary fission, what is the mean division time?
-the mean time it takes for a bacterial cell to divide
74
what does 'culturing' bacteria mean?
-growing them in a controlled laboratory
environment
75
what conditions do bacteria need to grow?
-warmth, nutrients, moisture and sometimes oxygen
76
state the four adaptions a sperm cell has in order to carry out its function
-sperm cells contain half the genetic information of a normal adult cell
-sperm cells have a long tail which allow them to swim to the ovum + they are streamlined to make this easier
-sperm cells have lots of mitochondria which provide energy needed for swimming
-sperm cell contain enzymes which allow them to digest their way through the outer layer of the ovum
77
how are nerve cells adapted to carry out their function
-myelin insulates the axon and speeds up the transition of nerve impulses
-the end of the axon has synapses which are junctions that allow the impulse to pass from one nerve cell to another
-dendrites increase the surface area so that other nerve cells can connect more easily
78
describe the adaptations of muscle cells
-muscle cells contain protein fibres which contract , allowing them to change their length
-when a muscle cell contracts, these protein fibres shorten , decreasing the length of the cell
-muscle cells have lots of mitochondria which provide energy for muscle contraction
79
what is differentiation?
-the process by which a cell becomes specialised
80
name an adaption of a root hair cell
-root hair increases the surface area
81
why do root hair cells not carry out photosynthesis?
-they do not contain chloroplasts because they are underground
82
how are xylem specialised?
-they have very thick walls containing lignin which provides support to the plant.
-because cell walls are sealed with lignin it causes the xylem cells to die
-the end walls between the cells have broken down so the cells now form a long tube
83
where are xylem found?
-in the plant stem and they form long tubes
84
what do xylem carry?
-water and dissolved minerals from the roots to the leaves
85
what do phloem tubes transport?
-dissolved sugars up and down the plant
86
how are phloem cells specialised?
-phloem vessel cells have no nucleus and only limited cytoplasm
-the end walls of the vessel cells have pores called sieve plates
-this allows dissolved sugars to move through the cell interior
-each phloem vessel cell has a companion cell connected by the pore
87
what is the definition of active transport?
-the movement of substances from a more dilute solution to a more concentrated solution against the concentration gradient
88
what are two ways diffusion differs from active transport?
-in diffusion the particles move down the concentration gradient while for active transport the particles moved against the concentration gradient
-active transport requires energy from respiration while diffusion does not
89
what are two examples of active transport?
-active transport carries sugars from the lumen of the small intestine into the bloodstream
-in a root hair cell, the concentration of ions in the soil is lower than the concentration inside the root hair cell
-active transport is used to move the ions into the cell, these ions are then transported into the xylem vessel and moved into the leaf
90
describe bone marrow transplant
-the patient's existing bone marrow is destroyed using radiation
-the patient then receives a transplant bone marrow from a donor
-the stem cells in the bone marrow now divide and form new bone marrow, they also differentiate and form blood cells
91
what are two problems with bone marrow transplants?
-the white blood cells produced by the donated bone marrow could attack the patient's body
-the is a risk of viruses
92
describe the stages of the cell cycle
-in the first stage the DNA replicates to form two copies of each chromosome
-the cell also grows and copies its internal structures such as mitochondria and ribosomes
-in the second stage mitosis takes place, one set of chromosomes are pulled to each end of the cell and the nucleus also divides
-in the final stage the cytoplasm and cell membrane divide to form two identical cells
93
what happens when organisms get larger?
-their surface area : volume ratio decreases which is a problem for multicellular organisms
94
why is a smaller surface area: volume ratio a problem for multicellular organisms?
-their surface area is not large enough for their volume as it leads to less oxygen by diffusion
95
how do fish get their oxygen?
-the oxygen-rich water passes into the mouth.It then flows over gills where the oxygen is transported into the bloodstream
96
describe how the blood becomes oxygenated for fish?
-deoxygenated blood passes into the filament.
-oxygen diffuses from the water into the blood
-oxygenated blood returns to the body
97
what are 3 adaptations that filaments have for increased rate of diffusion?
-the filaments give the gills a massive surface area
-the filaments also have a thin membrane to provide a short diffusion pathway
-the filaments have an efficient blood supply that ensures the concentration gradient is always high
98
how does diffusion affect oxygen and carbon dioxide
-oxygen molecules move into the cell by diffusion
-carbon dioxide moves out of the cell by diffusion
99
what is another molecule that diffuses out of cells other than carbon dioxide?
-urea, a waste product produced inside cells
-it diffuses out of the cells into the blood plasma and is excreted by the kidneys
100
what would happen if we placed an animal cell in water?
-osmosis would take place
-water will move by osmosis from outside the cell to inside the cell
-water moving in would cause the cell to expand - it could even burst
101
what would happen if we place an animal cell in a concentrated solution?
-water will move out of the cell by osmosis and the cell will shrink
102
what would happen if we placed a plant cell in water?
-the water will move into the cell by osmosis and cell will expand
-the cell wall prevents the plant cell from bursting, instead the cell becomes turgid
103
what would happen if we placed the plant cell into a concentrated solution?
-water moves out of the plant cell by osmosis
-this causes the shrink to shrink, it has become flaccid
104
describe how to use an optical microscope to view a prepared slide
-we place slide onto stage + use clips to hold slide in place
-we then select the lowest power objective lens
-we turn the coarse focussing dial to position the objective lens so it almost touches the microscope slide
-we look down through the eyepiece and slowly turn the coarse focussing dial to increase the distance between the objective lens and the slide
-we use the fine focusing dial to bring cells into clear focus
-select a higher power objective lens
-adjust the fine focussing dial to bring the cells back into focus
-use pencil to make a clear, labelled drawing of cells
105
how do we calculate the the total magnification?
-we multiply the magnification of the eyepiece lens by the magnification of the objective lens
106
describe how to prepare an uncontaminated bacterial culture using aseptic technique
-first sterilise all petri dishes, bacterial nutrient broth and agar
-this kills any unwanted microorganisms and prevents contamination
-bacteria are normally transferred into the culture using an inoculating loop
-we sterilise the inoculating loop by passing it through a bunsen burner flame
-we attach the lid of the petri dish using adhesive tape. This stops the lid from falling off and unwanted microorganisms entering
-we then place the agar plate upside down into an incubator. This stops moisture from dripping down onto the bacteria and disrupting the colonies
-we incubate bacteria at 25 degrees to reduce chances of harmful bacteria growing
107
describe how to investigate the effects of antibiotics on bacterial growth
-clean the bench with disinfectant solution. This kills microorganisms that could contaminate our culture
-we sterilise an inoculating loop by passing it through a bunsen burner flame
-open a sterile gel plate near a bunsen burner flame. The flame kills bacteria in the air
-use the loop to spread the chosen bacteria evenly over the plate
-place sterile filter paper discs containing antibiotic onto the plate
-incubate the plate at 25 degrees
108
how can we measure the effect of the antibiotic?
-by calculating the area of the zone of inhibition using the equation πr²
109
describe how to investigate the effect of osmosis on plant tissue
-we peel the potato because potato skin can affect osmosis
-use a cork borer to produce three cylinders of potato
-using a cork borer makes all of the cylinders have the same diameter
-use a scalpel to trim the cylinders to the same length
-measure the length of each cylinder using a ruler and the mass of each cylinder using a balance
-place each cylinder into a test tube and add 10 cm^3 of 0.5 molar sugar solution to the first test tube
-add 10cm^3 of 0.25 molar sugar solution to the second test tube and 10cm^3 of distilled water to the third test tube
-leave the potato cylinders overnight to allow osmosis to take place
-remove the potato cylinders and gently roll them on paper towel to remove any surface moisture
-measure the length and mass of the cylinders again
110
what is the equation to calculate percentage change?
% change = (change in value/ original value) x 100
