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GSCE BIOLOGY > B1 CELL BIOLOGY > Flashcards

B1 CELL BIOLOGY Flashcards

1
Q

what are two types of cells?

A

-Eukaryotic cells are more complex and include animal and plant cells
-Prokaryotic are much more smaller and simpler eg bacteria

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2
Q

what are 5 subcellular structures of animal cell/ plant cell?

A

nucleus = contains genetic material and controls activities of cell

cytoplasm = jelly like substance where most of chemical reactions happen. it contains enzymes that control these chemical reactions

cell membrane= holds cell together and controls what goes in and out.

mitochondria = where most aerobic respiration happens

ribosomes = these are where proteins are made.

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3
Q

what are 3 extra subcellular structure a plant cell has but animal cell doesn’t have?

A

cell wall = made a cellulose. it supports cell and strengthens it

permanent vacuole = contains cell sap ( a weak solution of sugar and salts)

chloroplasts = this where photosynthesis occurs. contains a green substance called chlorophyll which absorbs the light needed for photosynthesis.

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4
Q

what are subcellular structures of bacteria cell?

what is different about bacteria cell?

A

cytoplasm
cell membrane
cell wall
plasmids = small ring of DNA

difference
- they don’t have a “true” nucleus instead they have a single strand of DNA that floats freely in cytoplasm

don’t have chloroplast or mitochondria.

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5
Q

what are microscopes?
what are light microscopes and the problems?

A

Microscopes allow us to magnify
-Light microscopes use light and lenses to form an image (make it look bigger).They let us see individual cells and large subcellular structures like nuclei
Problems:
-Limited resolution
-Limited magnification

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6
Q

what are electron microscopes?
what is resolution?
what are the benefits of it?

A

-Electrons use electrons instead of light to form an image
Benefits:
-Higher magnification
-Higher resolution
-Lets us see small smaller things in more detail like the internal structure of mitochondria and chloroplasts.
-They even let us see tinier things like ribosomes and plasmids
-Resolution is the ability to distinguish between 2 points

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7
Q

How to write figures in standard form?

A

example- mitochondrion is approx 0.0025 mm long. Write this figure in standard form

1)First number needs to be between 1 and 10 so the decimal point needs to move after 2
2)Count how many places the decimal point has moved -power of 10.Dont forget the decimal point has moved right

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8
Q

what is the magnification formula?

A

image size divided by real size

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9
Q

how do you prepare your slide? Use onion cells as e.g

A
  1. Add a drop of water to the middle of clean slide
  2. cut up onion and separate it into layers . Use tweezer to peel of some epidermal tissues
    3.place epidermal tissue into water on the slide
  3. add a drop of iodine solution. Iodine solution is a stain. Stains are used to highlight objects in cell by adding colour
  4. place a cover slip . Stand the coverslip upright next to water droplet. Carefully tilt it lower and try not to get air bubbles under there - it will obstruct your view.
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10
Q

How do you prepare your slide?

A
  1. Clip the slide you prepared onto the stage
  2. select the lowest -powered objective lens
  3. use the coarse adjustment knob to move the stage up to just below the objective lens
  4. look down the eyepiece and move the stage downwards until the image is roughly in focus
  5. adjust the focus with the fine adjustment knob until you get a clear image
  6. if you need to see the slide with greater magnification swap to high powered objective lens
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11
Q

How to draw your observation?

A
  1. Draw what you see under the microscope using a pencil with sharp point
    2.make sure your drawing takes up at least half the space and that is drawn with clear, unbroken lines
  2. your drawing should not include any colouring or shading
    4.if you are drawing cells, the subcellular structures should be drawn in proportion
    5.Write down what your observing and magnification
    6.label the important features of tour drawing with straight, uncrossed lines.
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12
Q

What is differentiation?
what are cells that are undifferentiated?

A

-is process by which a cell changes to become specialised for its job
-they are called stem cells

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13
Q

what are 5 types of specialised cells ?
what are sperm cells?

A

-Sperm cells
-nerve cells
-muscle cells
-root hair cells
-phloem and xylem cells

sperm cells: specialised to get male dna to female dna
-has long tail and streamlined head to help it swim to the egg
-lot of mitochondria in cell to provide energy needed.

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14
Q

What are nerve cells?

A

-specialised for rapid signalling
-carry electrical signals
-long and have branched connections at their end to connect to other nerve cells and form networks.

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15
Q

What are muscle cells specialised for?

A

-specialised for contraction
-These cells are long ( have space to contract). These cells are long and contain lots of mitochondria to generate energy needed for contraction

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16
Q

What is a root hair cell?

A

-specialised for absorbing water and minerals
-Grow into long “hairs” that stick out in soil and gives plant big surface area for absorbing water and mineral ions

17
Q

What are phloem and xylem cells?

A

-specialised for transporting substances

-Form phloem and xylem tubes which transport substances such as food and water around the the plants. To form tube the cells are long and joined end to end. Xylem cells are hollow in the centre and phloem cells have very few subcellular structures so that stuff can flow through them.

18
Q

what are chromosomes and what does each chromosome carry?
how much copies do body cells normally have?
How many pairs of chromosomes from a human cell?

A

-They are coiled up lengths of DNA
-Each chromosomes carry a large number of genes
-They have two copies of each chromosomes
-23 pairs of chromosomes from a human cell

19
Q

what does body cells in multicellular organisms divided to produce?
what is the stage of the cell cycle when the cell divides?
what do multicellular organism use mitosis for?
what does the end of the cell cycle result in?

A

CELL CYCLE- GROWTH/DEVELOPMENT/REPAIR
-They divided to produce new cells as part of a series of stages called the cell cycle
-Stage is mitosis
-They use mitosis to grow and replace cells that have been damaged
-End of the cell cycle results in 2 new identical cells to the original cell with the same number of chromosomes

20
Q

what is the 3 steps for growth and dna replication?
what is the 3 steps for mitosis?

A

1) In a cell that’s not dividing dna is all spread out in long strings
2)Before it divide’s cell has to grow and increase the amount of subcellular structures such as mitochondria and ribosomes
3) It then duplicates its DNA.The dna is copied and forms X-shaped chromosomes.Each arm of the chromosomes is an exact duplicate of the other
-Once the contents and dna has been copied the cell is ready for mitosis
4) Chromosomes line up at the centre and the cell fibres pull them apart.2 arms of each chromosomes go to opposite ends of the cell
5) Membranes form around each sets of the chromosomes.These become the nuclei of 2 new cells-nucleus has divided
6) Lastly cytoplasm and cell membrane divided

The cell has now produced 2 new daughter cells.Daughter cells contain exactly the same dna-they’re identical. Dna is also identical to the parent cell

21
Q

What are stem cells? + where can they be found?
what is differentiation?

A

-undifferentiated cells they can differentiate into any type of cells
-Differentiation is the process by which a cell changes to become specialised for it’s job
-they can be found in early human embryos and for adults they can be found on certain places like bone narrow
-stem cells from embryos and bone narrow can be grown in a lab to produce clones and made to differentiate.

22
Q

What are 3 ways stem cells can be able to cure disease ? what is a risk?

A

-stem cells transferred from bone narrow of healthy person can be used to replace faulty blood cells
-embryonic stem cells - can also replace faulty cells in sick people for e.g insulin producing cells for e.g people with diabetes
-Therapeutic cloning - embryo can have the same genetic information as the patient so this means stem cells produced from it would contain the same genes and wouldn’t be rejected
RISK
stem cells may be contaminated with virus which can be passed on.

23
Q

Why are some people against stem cells research?

A

-embryos shouldn’t be used because it can be potential human life however they could argue say embryos used are usually unwanted ones from fertile clinics which if they weren’t used for research they would probably be destroyed
-in some countries stem cells research is banned.

24
Q

How can stem cells be used to produce identical plants?

A

-stem cells are found in meristem and meristem tissues can differentiate into any type of plant and this can be used to produce clones of whole plant quickly and cheaply
-used to grow more plants of rare species and also be used to grow crops of identical plants that have desired features farmers e,g disease resistance.

25
Q

What is diffusion? + where does it happen?
What happens if has the bigger the concentration gradiaent and higher temperature ?

A

-Spreading of particles from an area of high concentration to area of lower concentration.
-It happens in both solution and Gases - this because particles are free to move about
-bigger concentration GRADIENT = the faster diffusion rate
-high temp = faster diffusion rate because particles have more energy

26
Q

What does cell membrane do during diffusion?

A

-they hold cell together but they let stuff in and out
-Only small molecules can diffuse through membrane for e.g oxygen, glucose and amino acids however big molecules like starch and protein can’t fit through membrane.
-The larger the surface area=faster diffusion rate

27
Q

What is osmosis?
what is practical on osmosis?

A

-type of diffusion
-movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of lower water concentration
-water molecules pass through both ways this because water molecules move about randomly

1) Cut up a potatoe into identical cylinders and you get a beaker with different sugar solutions. One solution should be pure water and the other one should be very concentrated sugar solution e.g 1 mol/ dm3 , 0.2 mol dm3, o.3 mol dm3 etc
2)measure the mass of cylinders
3)dry them out with paper towel and measure their masses again. If cyclinder has drawn in water the mass will increase. If cyclinder have decrease in mass the water has been drawn out.
3) Dependent variable = chip mass independent variable = concentration of sugar used. They must be kept same in each experience or it wont be a fair test.
4) In any experiments errors eg if some potato cyclinder were not fully dried excess water would give a higher mass or if water evaporated from the beakers concentration of sugar solutions water evaporated from the beaker.You can reduce effects of these errors by repeating experiments and caculating a mean percentage change

28
Q

what does active transport allow plants to do?
how can active transport happen in humans eg?
why is active transport used in the gut?
what happens when theres a higher concentration of glucose and amino acids in the gut?
what happens when there is a lower conc of nutrients in the gut than in blood?

A

-Allow plants to absorb minerals from a very dilute solution against a concentration gradient.Essential for it’s growth but active transport needs ENERGY for respiration
-Active transport in humans eg taking glucose from gut and from kidney tubes
-Active transport is used in the gut when is there lower concentration of nutrients in the gut but a higher conc. of nutrients in the blood
-When there’s a higher concentration of glucose and amino acids they diffuse naturally in the blood
BUT..
sometimes there a lower conc. of nutrients in the gut than there is in blood
This means conc gradient is wrong way

29
Q

what does active transport to do what in the blood?
what does it mean?

A

-Allow nutrients to be taken into the blood despite the fact that concentration gradient is the wrong wsy
-This means that glucose can be taken into the bloodstream when its concentration in the blood is already higher than in the gut.It can be transported to cells where it’s used for respiration

30
Q

what can cells use diffusion for?
what is the surface area to…what?

A

-They can use it to take in substances they need and get rid of waste products
eg oxygen and carbon dioxide are transferred between cells and the environment during gas exchange another eg is in humans urea diffuses from cells into the blood plasma
-SURFACE AREA TO VOLUME RATION
SA:V

31
Q

what do gases and dissolved substance diffuse in single celled organisms?
what do multicellular organisms

A

-In single celled organisms gases and dissolved substances can diffuse directly into cell
-Its because they have a large surface area compared to their volume
-Multicellular have a smaller surface area compared to their volume- not enough substances can diffuse from their outside surface to supply their entire volume.This means that they need some sort of exchange surface for efficient diffusion

32
Q

what are exchange surfaces adapted to maximise effectiveness? (3)

A

-they have a thin membrane so substances only have short diffusion to diffuse
-they have large surface area so lot of a substance can diffuse at once
-exchange surfaces in animals have lots of blood vessels

33
Q

what is the 2 steps of gas exchange?
Alveoli are specialised to maximise the diffusion of o2 and co2 they have?

A

1) Job of the lungs is to transfer oxygen to the blood and to remove waste carbon dioxide
2)To do this lungs contain millions of little air sacs alveoli where gas exchange takes place

ALVEOLI
-They have an enormous surface area
-Moist lining for dissolving gases
-Very thin walls
-Good blood supply

34
Q

where is the villi found?
what are 3 features of it??

A

-Villi are found in the small intestine
-They increase area so that digested food can be absorbed much more quickly into blood
-They also have a single layer of surface cells and a very good blood supply to assist quick absorption

35
Q

what 2 places does carbon dioxide diffuse?
what is the underneath of the leave and what is it covered in?
what are other 2 things that diffuse out?
what is the size of the stomata controlled by?
what is the flattened shape of the leaf do?
what does the walls of the cells inside the leaf?

A

-They diffuse into air spaces within the leaf then they diffuse into the cells.The leafs structure is adapted so that this can happen easily
-Underneath leaf is an exchange surface and it’s covered in tiny holes called stomata
-Oxygen and water vapour also diffuse out
-The size of stomata are controlled by guard cells.These close stomata if the plant is losing water faster
-The flattened shape of the leaf increases the area of this exchange surface
-Walls of the cells inside the leaf form another exchange surface.The air spaces inside the leaf increases the area of this surface

36
Q

what are the gas exchange surface in a fish?
where does the water enter?
what is each gill made of?
what are covered in and does it do?(2)
where does the blood flow?
what is concentration of oxygen in water higher or lower?

A

-Gills
-The water enters fish through the mouth and passes out through the gills
-Each gill is made of lots of thin plates called gill filaments which give a big surface area for exchanges of gases
-Gil filaments are covered in lots of tiny structures called lamellae which increase surface area
-Lamellae have lots of blood capillaries to speed up diffusion
-They also have a thin surface layer of cells to minimise the distance.
-Blood flows through the lamellae in 1 direction and water flows over in the opposite direction.This maintains a large concentration gradient
-Concentration of oxygen in the water is always higher than that in the blood

GSCE BIOLOGY (6 decks)

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