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GCSE Biology Paper 1 > Cell Biology > Flashcards

Cell Biology Flashcards

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1
Q

What is the difference between light microscopes and electron microscopes?

A

-Light -> use light and lenses. Let us see individual cells and large subcellular structures
-Electron -> use electrons. Have a higher magnification and resolution and let us see much smaller things in more detail

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2
Q

What is the formula for finding the magnification of an image?

A

Magnification = Image size / Real size

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3
Q

How do you prepare a microscope slide?

A

-add a drop of water
-Place onion epidermal tissue in the water on the slide using tweezers
-Add a drop of iodine solution
-place cover strip on top try not to get any air bubbles

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4
Q

How do you look at a slide using a light microscope?

A

-Clip the slide into the stage
-use lowest powered objective lens to start
-move stage up using coarse adjustment knob
-use same knob to put it roughly into focus
-use fine adjustment knob to put it into focus

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5
Q

What is cell differentiation and when does it take place?

A

-The process of cells developing to become specialised for their specific job
-Happens mainly in the early stages for animal cells
-Happens at any stage for plant cells

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6
Q

How are sperm cells specialised?

A

-long tail
-streamlined head
-lots of mitochondria for energy
-enzymes to digest through egg cell membrane

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7
Q

How are nerve cells specialised?

A

-long to cover distance
-branched connections at their ends to form a network

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8
Q

How are muscle cells specialised?

A

-long so they have space to contract
-lots of mitochondria for energy

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9
Q

How are root hair cells specialised?

A

big surface area for absorbing water and mineral ions from the soil

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10
Q

What are chromosomes?

A

Coiled up lengths of DNA molecules found in the nucleus of cells, containing a large number of genes

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11
Q

How many pairs of chromosomes are in a human cell?

A

23 pairs

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12
Q

What is mitosis?

A

The stage of the cell cycle where it divides. It’s used to grow or replace damaged cells.

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13
Q

What happens in the growth and DNA replication stage of the cell-cycle?

A

-the cell grows and increases its number if subcellular structures
-it duplicates its DNA
-The copied DNA forms X-shaped chromosomes where each arm is an exact duplicate of the other

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14
Q

What happens in the mitosis stage of the cell-cycle?

A

-chromosomes line up in the middle of the cell and cell fibres pull them apart, each arm goes to the opposite side
-Membranes form around each set
-the cytoplasm and cell membrane divide
-divides into 2 daughter cells

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15
Q

What is the name of the process where prokaryotic cells replicate?

A

Binary fission

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16
Q

How does binary fission work?

A

-plasmids replicate
-cell expands and circular DNA strands go to opposite sides of the cell
-cytoplasm starts dividing
-new cell wall starts to form
-divides into 2 daughter cells

17
Q

What is mean division time?

A

The average amount of time it takes for one bacterial cell to divide into two

18
Q

How are bacteria grown in a lab?

A

In a culture medium (nutrient broth solution or agar jelly) with all the nutrients they need to grow

19
Q

How do you make an agar plate?

A

-hot agar jelly is poured into petri dishes
-when it sets wire loops or pipettes are used to put microorganisms in
-bacteria will form visible colonies

20
Q

How can you investigate the effect of antibiotics on bacterial growth?

A

-evenly cover agar plate with bacteria
-soak paper disks in different antibiotics and put them on top
-antibiotic resistant bacteria will continue growing
-non resistant strains will die and create a clear patch (inhibition zone)
-larger inhibition zone = more effective antibiotic
-use paper soaked in sterile water as a control

21
Q

How do you find the size of an inhibition zone?

A

By measuring its diameter and use this to find the area

22
Q

What are stem cells and where are they found?

A

-undifferentiated cells with the potential to turn into any type of cell
-found in early human embryos
-some places in adults (e.g. bone marrow) but they can only turn into certain types of cells (e.g. blood cells)

23
Q

How can stem cells be used to cure disease?

A

They can be transferred from a healthy adult or an embryo to replace faulty cells in an ill person (e.g. insulin producing cells for a diabetic)

24
Q

How does therapeutic cloning work?

A

An embryo is made with the same genetic information as the patient so it wouldn’t be rejected by the body.

25
Q

What is the ethical debate around stem cells?

A

Whether the embryo which is a potential human life should be valued more than curing the existing patients who are suffering

26
Q

How are the stem cells found in the meristems of plants used?

A

-producing clones
-grow more plants of a rare species
-grow crops of identical plants

27
Q

What is diffusion?

A

The gradual movement from areas of high concentration to areas of low concentration. It happens in both solutions and gases

28
Q

How does diffusion take place with cells?

A

Very small particles like oxygen flow through the cell membrane moving randomly both in and out. The larger the surface area of the membrane, the faster diffusion will happen

29
Q

What is Osmosis?

A

The movement of water molecules across a partially permeable membrane from an area of high concentration to areas of low concentration.

30
Q

How can you find out how sugar affects plant tissue?

A

-cut up potato into identical cylinders
-measure their initial mass
-put into beakers containing sugar solutions with different concentrations and leave for a while
-Take them out, dry them and measure their mass again
-If they gained water the mass will increase and if the lost water it will decrease

31
Q

How do root hair cells take in minerals using active transport?

A

-they absorb minerals from a dilute solution using a concentration gradient
-this requires energy from respiration

32
Q

How does the human body use active transport?

A

-when there’s more nutrients in the gut than in the blood they diffuse naturally into the blood stream
-sometimes its the other way around so active transport is used instead

33
Q

What is an example of cells using diffusion to exchange substances with their environments?

A

Oxygen and Carbon dioxide are transferred between cells during gas exchange

34
Q

Why is it easy for substances to diffuse in and out of single-celled organisms?

A

Because they have a larger surface area to volume ratio so enough substances can be exchanged across the membrane to supply the volume of the cell

35
Q

Multicellular organisms need exchange surfaces for efficient diffusion. How are these adapted to maximise effectiveness?

A

-thin membrane -> short distance to diffuse
-large surface area -> more can diffuse at once
-lots of blood vessels -> to get things in and out quicker

36
Q

How are the alveoli specialised to maximise the diffusion of O2 and CO2?

A

-enormous surface area
-moist lining for dissolving gasses
-very thin walls
-good blood supply

37
Q

How are villi specialised to increase the surface area of the small intestine to speed up food absorption?

A

-single layer of surface cells
-very good blood supply

38
Q

How are leaves specialised for the exchange of substances?

A

-flat shape means large surface area
-walls of the cells act as exchange surface
-water evaporated from the cells and then escapes by diffusion

39
Q

How do gills act as a gas exchange surface for fish?

A

-water enters through the mouth and passes the gills
-oxygen diffuses into blood and carbon dioxide diffuses into the water
-each one is made of gill filaments which increase the surface area
-lots of blood capillaries and thin layer of cells

GCSE Biology Paper 1 (4 decks)

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