P1 - Cell Biology Flashcards
What are 2 light microscope advantages?
- Easy to use
- Relatively cheap
What’s 1 electron microscope advantage?
- Very good resolution
What’s 1 light microscope disadvantage?
- Limited resolution
What are 2 electron microscope disadvantages?
- Hard to use
- Expensive
What organelles do plant cells have that animal cells do not?
- Cell wall
- Vacuole
- Chloroplasts
Are prokaryotic cells larger or smaller than eukaryotic cells?
Smaller
Is a bacterial cell a eukaryotic cell or prokaryotic cell?
Prokaryotic
Are animal and plant cells eukaryotic or prokaryotic cells?
Eukaryotic
Where’s the genetic material in prokaryotic cells?
- Loop of DNA (not enclosed in a nucleus)
- Plasmids
What’s the function of the nucleus?
To enclose the genetic material
The _________ is a watery solution where chemical reactions take place.
Cytoplasm
What is the function of the cell membrane?
It controls what molecules can enter and exit the cell
What is the function of the mitochondria?
Where aerobic respiration occurs
What is the function of ribosomes?
The site of protein synthesis
Do animal or plant cells have a regular shape?
Plant cells
What is the function of chloroplasts?
They contain chlorophyll and are the site of photosynthesis
What is the function of the cell wall?
To provide structure and support
What is the function of the vacuole?
It gives the plant its shape
+ It’s filled with cell sap
What is the cell wall made from and what does it do?
It’s made from cellulose and this strengthens the cell
What is a specialised cell?
A cell which has adapted to carry out its particular function
What’s the purpose of a tail in a sperm cell?
To swim to the ovum (egg cell)
What’s the purpose of mitochondria in a sperm cell?
To provide energy needed for swimming
What’s the purpose of enzymes in a sperm cell?
To digest their way through the outer layer of the ovum (egg cell)
What’s the purpose of the axon in a nerve cell?
It carries electrical impulses from one part of the body to another
What’s the purpose of myelin in a nerve cell?
It insulates axon and speeds up the transmission of nerve impulses
What’s the purpose of synapses in a nerve cell?
Sypnases are junctions, these allow impulses to pass from one nerve cell to another
What’s the purpose of dendrites in a nerve cell?
Increase surface area so that other nerve cells can connect easier
What kind of fibre do muscles contain to change their length for contraction?
Protein
Why are muscle cells packed full of mitochondria?
To provide energy for muscle contraction
What’s the function of root hair cells?
The root hair increases the surface area of the root, so it can absorb water and dissolved minerals more effectively
Why do root hair cells not contain chloroplasts?
Because they are underground
Extra: Chloroplasts which contain chlorophyll are the site of photosynthesis therefore it’s not needed underground
Where in a plant are xylem found?
In the plant stem
Do xylem carry water or sugar?
Water
What do the tubes in xylem carry from the roots to the leaves?
Water and dissolved minerals
What does the thick walls containing lignin in xylem provide?
It provides support
What happens to the xylem because the cell walls are filled with lignin?
It causes the xylem to die
Why do xylem cells have no nucleus, cytoplasm, vacuole or chloroplasts?
It makes it easier for water and minerals to flow
Do phloem carry water or sugar?
Sugar
Do phloem tubes carry dissolved sugars one or both ways?
Carry dissolved sugars up and down the plant
In phloem, the end walls of the vessel cells have pores called ____ _____. What do they allow?
Sieve plates, they allow dissolved sugars to move through the cell interior
TRUE OR FALSE: Phloem cells have no nucleus and lots of cytoplasm
FALSE: Phloem cells actually have no nucleus and LIMITED cytoplasm
Does each cell or every other cell in phloem have a companion cell connected by pores?
Each cell
In the companion cell of phloem, what do the mitochondria provide?
Provide energy to the phloem vessel cell
Possible 5 marker:
How do we use a prepared slide?
Hints:
1- stage + clips
2- objective lens + coarse focusing dial
3- eyepiece + coarse focusing dial
4- fine focusing dial
5- eyepiece
6- objective lens
1- Place the slide onto the stage and use clips to hold it in place
2- Adjust the position of the lowest objective lens to almost touch the slide by turning the coarse focusing dial
3- Look through the eyepiece and slowly turn the coarse focusing dial to increase distance
4- Use the fine focusing dial once it’s in focus to bring cells into clearer focus
5- Look through the eyepiece and examine what you see
6- For more detail use an objective lens with a higher magnification and repeat
TRUE OR FALSE: Bacteria are prokaryotes
TRUE
TRUE OR FALSE: In bacterial cells, genetic information is not enclosed in a nucleus
TRUE
How many bacterials cells does one bacterial cell split into? What is this called?
- Splits into two bacterial cells
- Binary fission
Bacteria can carry out binary fission once every ______ minutes as long as they have enough ________ and temperature is suitable
- Twenty
- Nutrients
What’s the equation for the number of bacteria?
Number of bacteria = 2^n
n = number of rounds of division
What does a nutrient broth solution contain?
All the nutrients the bacteria need to grow and divide
Why is the broth in a nutrient broth solution cloudy?
It contains a very large number of bacteria
What temperature do we incubate bacteria at? Why at this temperature?
25 degrees celsius, it reduces the chances that harmful bacteria will grow
Possible 6 marker:
How do we set up to see the effects of antibiotics in bacterial growth?
Hints:
1- Disinfectant
2- Inoclulation loop + bunsen burner
3- Agar gel plate + bunsen burner
4- Inoculating loop
5- Filter paper discs
6- Incubate
1- Clean the area with disinfectant to kill microorganisms.
2- Sterilise an inocluating loop by passing it through a bunsen burner flame
3- Open a sterile agar gel plate near a bunsen burner as the flame kills bacteria in the air
4- Use the loop to spread bacteria evenly over the plate
5- Place the sterile filter paper discs containing antibiotic onto the plate
6- Incubate at 25 degrees celsius
How do you work out the area of the zone of inhibition in an agar gel plate after it’s been left for days?
Area = pi x r^2
Where do we find chromosomes?
In the molecule of DNA which is enclosed in a nucleus
How many pairs of chromosomes do human body cells contain?
23 pairs
Certain cells home chromosomes that are not paired, what are these called?
Gametes
How many genes do most chromosomes contain?
Hundreds
What do chromosomes determine for us?
They carry a large number of genes so they determine many of our features
What 2 ways can cells divide?
- Mitosis
- Meiosis
What’s the first stage of the cell cycle?
The DNA replicates to form 2 copies of each chromosome
The cell grows and copies its internal structures
What’s the first stage of the cell cycle called?
Interphase
What’s the second stage of the cell cycle?
One set of chromosomes is pulled to each end of the cell
The nucleus also divides
What’s the second stage of the cell cycle called?
Mitosis
What’s the final/third stage of the cell cycle?
The cell divides into two daughter cells
What’s the final/third stage of the cell cycle called?
Cytokinesis
What are 3 mitosis functions?
- Essential for growth and development of multicellular organisms
- Takes place when an organism repairs itself
- Happens during asexual reproduction
How are humans made (stem cell answer version and explanation, 3 points)?
- Fertilisation (sperm cell joins with an ovum)
- The fertilised ovum undergoes mitosis and forms an embryo
- They continue to undergo mitosis and form specialised cells
What’s an embryo?
A ball of cells
What is it called when cells specialise?
Differentiation
What is a stem cell?
An undifferentiated cell which can produce more cells of the same type and can differentiate
What do stem cells in bone marrow do?
Differentiate to form cells found in our blood such as red blood cells, white blood cells and platelets
What’s a cancer of the bone marrow called (starting with l)?
Leukaemia
How do we treat leukaemia using bone marrow transplants and what’s the process?
- Radiation is used to destroy the patient’s existing bone marrow
- The patient receives a bone marrow transplant from a donor
- The stem cells divide and form new bone marrow and differentiate and form blood cells
What are 2 problems with bone marrow transplants?
- Compatibility: If the donor isn’t compatible the white blood cells produced by the donated bone marrow could attack the patient’s body
- Viruses could be passed from the donor to the patient
What’s the process of therapeutic cloning?
- An embryo is produced with the same genes as the patient
- Stem cells from the embryo are transplanted without being rejected by the patient’s immune system
- Once inside the patient, the stem cells differentiate and replace cells that have stopped working correctly
What is therapeutic cloning useful for?
A range of medical conditions such as diabetes or paralysis
Why can’t some people undergo therapeutic cloning?
Due to ethical and/or religious objections to the procedure
Where is meristem tissue in a plant?
Roots and buds
TRUE OR FALSE: Meristem tissue can differentiate into any type of plant tissue at only the start of a plant’s life
FALSE: Meristem tissue can differentiate into any type of plant tissue at any point
Can we use meristem tissue to produce clones of a plant quickly and cheaply?
Yes
Why might we need to produce clones of a plant quickly and cheaply?
To prevent extinction and to produce cloned crop plants for farmers
What’s the function of the cell membrane?
To control what enters and exits the cell
What is diffusion?
The movement of particles from an area of higher concentration to an area of lower concentration across a semi-permeable membrane
What are examples of particles that use diffusion?
Oxygen, carbon dioxide, urea
What do cells need for respiration?
Oxygen
What’s the function of mitochondria?
It’s the site of respiration
Oxygen is transported into the bloodstream from the _____
Lungs
What does urea diffuse out of the cells into?
Blood plasma
Extra: It’s later excreted by the kidneys
What are 3 factors that affect the rate of diffusion?
- Different in concentrations
(The greater the faster) - Temperature
(The higher the faster) - Surface area of the membrane
(The larger the faster)
What’s an example of a single-celled organism?
Amoeba
TRUE OR FALSE: As organisms get larger, the surface area to volume ratio falls sharply
TRUE
Extra: This presents a huge problem for multicellular organisms as their surface area isn’t large enough for their volume
Why can’t cells in the centre of an organism get enough oxygen from diffusion?
They are too far away from the surface
How are fish adapted for all their cells to receive enough oxygen?
- (Oxygen rich) Water passes into the mouth
- It flows over the gills where oxygen is transported into the bloodstream
- Deoxygenated blood passes into the filament
- Oxygen diffuses from the water into the blood
- Oxygenated blood returns to the body
Where do gases pass in and out of the blood in fish?
Fine filaments
TRUE OR FALSE: In fish, there’s a very small number of fine filaments
FALSE: In fish, there’s a very large number of fine filaments
What is osmosis?
Osmosis is the diffusion of water from an area of high concentration to an area of low concentration through a partially permeable membrane
What happens if we place an animal cell in water?
Water will move from the outside of the cell to the inside of the cell by osmosis so it will expand and possibly burst
What happens if we place an animal cell in a very concentrated solution?
Water will move out of the cell by osmosis and it will shrink
Why can’t plant cells burst by osmosis?
Because of the cell wall
During osmosis, what is it called when a plant cell becomes swollen?
Turgid
During osmosis, what is it called when a plant cell shrinks?
Flaccid
During the practical to work out the effects of osmosis on plant tissue we use potato, how do we prepare the potato?
Hints:
- Peel
- Cork borer
- Scalpel
- Measure
- First, we peel the potato as the skin can affect osmosis
- Use a cork borer to produce 3 cylinders of potato so that all the diameters are the same
- Use a scalpel to trim the cylinders to the same length (around 3cm)
- Measure the length and mass of each potato with a ruler and balance
During the practical to work out the effects of osmosis on plant tissue, what amount and what molar sugar solution do we use for each test tube?
First test tube: 10cm cubed of 0.5 molar sugar solution
Second test tube: 10cm cubed of 0.25 molar sugar solution
Third test tube: 10cm cubed of distilled water
During the practical to work out the effects of osmosis on plant tissue, how do we carry out the experiment after the potato cylinders have been left overnight?
- Leave the potato cylinders overnight to allow osmosis to take place
- Next, remove the potato cylinders and gently roll them on a paper towel to remove any surface moisture
- Measure the length and mass again
During the practical to work out the effects of osmosis on plant tissue, what is the potato in if it gains mass?
In water
During the practical to work out the effects of osmosis on plant tissue, what is the potato in if it loses mass?
A concentrated sugar solution
During the practical to work out the effects of osmosis on plant tissue, what causes there to be no change in the mass of the potato?
The concentration outside the cell is the same as the concentration inside so no overall osmosis takes place
Therefore, this concentration is the approximate concentration inside the cell
What is active transport?
Active transport is the movement of substances from a low concentration to a high concentration (against the concentration gradient)
Extra: This requires energy from respiration
Differences between diffusion and active transport:
Diffusion: Particles move ____ the concentration gradient
Active Transport: Particles are moved ______ the concentration gradient
Diffusion: Down
Active Transport: Against
Does diffusion or active transport require respiration?
Active transport
What is the cavity where foods are digested in the small intestine called?
Lumen
What do we find in the lumen? And give an example of one
The molecules produced when food’s digested, for example sugars such as glucose
Once sugars are carried into the lumen by active transport, where are they transported next?
The blood and then carried around the body
Why do lumen have lots of mitochondria?
To carry out respiration, providing the energy needed for active transport
What’s an example of an ion that root hair cells transport?
Ions such as magnesium
Why do plants need magnesium?
To make chlorophyll in the leaves
Once ions are carried into a root hair cell by diffusion, where are they transported to next?
The xylem vessel and are moved to the leaf
Why do root hair cells have lots of mitochondria?
To provide energy for active transport
