B1 - Cell Level Systems

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Give two functions of the cell membrane in an animal cell
It provides a selective barrier to control what goes in and out of the cell. It contains receptor molecules that are used for cell communication.
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A scientist wants to use a light microscope to view the cell walls of a colourless sample of plant tissue. Describe how she could prepare a slide containg the tissue, where the cell walls are visible.
Place a drop of mountant/water on the slide. Use tweezers to place the specimen on the mountant. Add a drop of stain. Carefully apply a cover slip over the specimen.
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Calculate the magnification of images viewed with an eyepiece lens magnification of x8 and an objective lens of x15.
Total magnification = eyepiece lens magnification x objective lens magnification. 8 x 15 = 120
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Why can DNA be described as a polymer?
It's a large complex molecule made up of nucleotides (monomers) joined together in a long chain.
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Which base does 'C' pair with in DNA?
G
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Explain the effect of base-pairing on the structure of DNA.
Each base forms cross links to a base on the opposite strand. This keeps the two DNA strands wound tightly together.
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Enzymes are described as having a 'high specificity' for their substrate. What is meant by this?
Enzymes have an active site, which the substrate has to fit into in order for the reaction to be catalysed. This means that enzymes usually one work with one substrate so they are very specific.
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Enzyme A's optimum pH is 4. Explain what might happen to enzyme A's activity in conditions above pH 4.
The enzyme's activity may slow down/stop because the enzyme may be irreversibly denatured. A pH higer than pH 4 will interfere with the bonds holding the enzyme together. This may change the shape of the active site so the substrate can no longer fit
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An enzyme-controlled reaction was carried out at 25ºC. After 60 seconds, 33cm³ of product had been released. Calculate the rate of reaction in cm³/second.
33 ➗ 60 = 0.55cm³/second
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Give the word equation for aerobic respiration.
glucose + oxygen ➝ carbon dioxide + water
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Name the product(s) of anaerobic respiration in plants.
Ethanol and carbon dioxide
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Why is it advantageous for organisms to respire aerobically rather than anaerobically?
Aerobic respiration produces much more ATP than anaerobic respiration
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Name the monomers that result from the breakdown of carbohydrates.
(simple) sugars
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Name the monomers that result from the breakdown of proteins.
amino acids
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Give one reason why it's important for the body to be able to break down large, complex molecules, such as starch.
So that energy can be transferred from their breakdown during respiration
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Explain how photosynthesis contributes to a plant's biomass.
Photosynthesis produces glucose which is used to make larger, complex molecules that make up the mass of the plant's living material/the plant's biomass
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List four features that animal and plant cells have in common.
They both contain a nucleus, cytoplasm, mitochondria and cell membrane
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Give two sub-cellular structures that are present in prokaryotic cells but not eukaryotic cells.
Chromosomal DNA and Plasmids
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How have electron microscopes been able to increase our understanding of sub-cellular structures?
Because they let us see much smaller things in more detail like the internal structures.
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Why is it important to take a thin slice of a sample before viewing it under a light microscope?
So light can go through it in order to see it clearly
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How can you calculate the magnification of an image if you don't know which lenses were used?
magnification = image size ÷ real size
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Give the initials of the four bases present in DNA.
A, T, G & C
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Describe the structure of a nucleotide.
Each nucleotide has the same sugar and a phosphate group. The base on each nucleotide varies (e.g. it could be A, G, C or T)
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What is a gene?
DNA that is divided up into short sections
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What does it mean when an enzyme has been 'denatured'?
It loses its shape and the substrate doesn't fit the active site anymore.
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Give two things that you could measure when investigating the rate of an enzyme-controlled reaction.
You could investigate how temperature affects enzyme activity and how fast a product appears or a substrate disappears
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What is respiration?
The process of transferring energy from the breakdown of glucose (a sugar).
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What is the function of ATP in a cell?
Stores the energy needed for many cell processes
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Is respiration an exothermic or an endothermic reaction?
Exothermic reaction
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Name the type of respiration that requires oxygen
Aerobic respiration
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Give an example of when lactic acid would be produced as a product of respiration
When you do vigorous exercise
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Which form of respiration transfers more energy per glucose molecule?
Aerobic respiration
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What type of polymer do you get when you join together simple sugars?
Starch and glycogen
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What type of biological molecule are oils?
lipids
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Name the basic units that lipids are made from
glycerol and three fatty acids
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In what part of a cell does photosynthesis take place?
chloroplasts
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Give three factors that can limit photosynthesis
Light, carbon dioxide and temperature
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Describe how you could investigate the effect of carbon dioxide concentration on the rate of photosynthesis
Dissolving different amounts of sodium hydrogen-carbonate (which gives off carbon dioxide) in water.
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Other cards in this set

Card 2

Front

A scientist wants to use a light microscope to view the cell walls of a colourless sample of plant tissue. Describe how she could prepare a slide containg the tissue, where the cell walls are visible.

Back

Place a drop of mountant/water on the slide. Use tweezers to place the specimen on the mountant. Add a drop of stain. Carefully apply a cover slip over the specimen.

Card 3

Front

Calculate the magnification of images viewed with an eyepiece lens magnification of x8 and an objective lens of x15.

Back

Preview of the front of card 3

Card 4

Front

Why can DNA be described as a polymer?

Back

Preview of the front of card 4

Card 5

Front

Which base does 'C' pair with in DNA?

Back

Preview of the front of card 5
View more cards

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