AQA A LEVEL BIOLOGY PAPER 1 2024 MAIN TEST

AQA A LEVEL BIOLOGY PAPER 1 2024 v v v v v v




MAIN TEST v v




What is the function of the cell membrane? - correct answer-To control what
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enters and leaves the cell, acts as a barrier between the cell and its
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environment.
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What structural feature of the cell membrane allows substances to enter/leave? -
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correct answer-Partially permeable
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What is the fluid mosaic model? - correct answer-States that a membrane is a
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fluid structure (because phospholipids are constantly moving) with a "mosaic" of
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various proteins embedded in it
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Describe the structure and function of phospholipids. - correct answer-Hydrophilic
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head and hydrophobic tail, arranged in a bilayer (heads face outwards, tails face
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inwards). Lipid-soluble substances only allowed to pass through.
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What is the function of cholesterol in the CSM? - correct answer-Make
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phospholipids pack more closely together, restricting the movement of the
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phospholipids, making the membrane less fluid/more rigid.
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What is simple diffusion? - correct answer-The (passive) movement of particles
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from an area of high concentration to an area of low concentration.
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v v m v m v m v m v m v m

, What is facilitated diffusion? - correct answer-The passive movement of a
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large/charged particle down its concentration gradient through a carrier/channel
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protein.
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What is the process of facilitated diffusion using a carrier protein? - correct
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v v m vm


vanswer-Large molecule binds to a carrier protein in membrane.
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Protein changes shape. v m v m v m


Protein releases the large molecule on the opposite side of the membrane.
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What is the process of facilitated diffusion using a channel protein? - correct
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answer-Channel proteins form pores in membrane.
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Charged particles can diffuse down their concentration gradients to the opposite
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side of the membrane.
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What are the factors affecting simple diffusion? - correct answer-Concentration
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gradient, thickness of exchange surface and surface area.
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What are the factors affecting facilitated diffusion? - correct answer-Number of
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transport proteins and strength of gradient.
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What is osmosis? - correct answer-Diffusion of water through a partially
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permeable membrane from an area of high water potential to an area of lower
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water potential.
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What are the factors affecting osmosis? - correct answer-Water potential
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vgradient.
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Thickness of exchange surface. v m v m v m v m


Surface area of exchange surface. v m v m v m v m




Outline a method for RP3 (investigation of osmosis using potato chips). - correct
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vanswer-Produce a series of dilutions from 1M sucrose solution (of a variety of
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vdifferent concentrations, 0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M).
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Use a cork borer to cut potatoes into identically-sized chips.
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Blot them dry with a paper towel and measure the mass of each using a mass
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vbalance.
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Place one chip into each of the sucrose solutions.
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Put the test tubes into a water bath at 30°C for 20 minutes.
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Take them out and reweigh the mass of the chips.
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Calculate the %change in mass for each chip. v m v m v m v m v m v m v m




What is active transport? - correct answer-The active process of moving
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molecules from an area of low concentration to an area of high concentration
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using ATP.
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Name one type of carrier protein and describe how it works. - correct answer-
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Co-transporters. v m


Bind two molecules at once.
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The concentration gradient of one of the molecules is used to move the other
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vmolecule against its own concentration gradient.
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