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biology (paper one) > transport in cells (topic 1) > Flashcards

transport in cells (topic 1) Flashcards

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1
Q

what is diffusion (2)

A
  • movement of particles
  • from high to low concentration
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2
Q

explain why the concentration of glucose in the small intestine changes between 100 cm and 300 cm (2)

A
  • carbohydrates are broken down and digested into sugars
  • which are then broken down by cabrohydrase or amylase
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3
Q

explain why the concentration of glucose in the small intestine changes between 300 cm and 700 cm (3)

A
  • absorption of glucose
  • into blood
  • by active transport
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4
Q

(2)

A
  • vacuole smaller
  • cytoplasm shrunk
  • cell wall curves inwards
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5
Q

a student put red blood cells into water, suggest what would happen to the cells (1)

A
  • water will diffuse in
  • cells will swell
  • cells will burst
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6
Q

(2)

A
  • have many root hairs
  • which give a large surface area for absorption
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7
Q

what is the function of the stomata

A
  • carbon dioxide in
  • oxygen out
  • control water loss
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8
Q
A
  • plant will wilt or droop
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9
Q
A
  • alveoli / alveolus
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10
Q

give two adaptations of the lungs that help the rapid absorption of oxygen into the blood

A
  • have many alveoli
  • large surfae area
  • good blood supply (as many cappilaries)
  • thin exchange surface or short diffusion pathway
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11
Q

describe why diffusion is important in plants and animals, give examples of the substances that are diffusing (6)

A

importance of diffusion:
- to take in substances for use in cell processes
- to remove the waste products from cell processes
examples of processes and substances in plants (max 2 marks):
- photosynthesis in plants: CO2 in
- photosynthesis in plants: O2 out
- water lost from leaves/transpiration
- water absorption by roots
examples of processes and substances in animals (max 2 marks):
- respiration in animals: O2 in
- respiration in animals: CO2 out
- food molecules absorbed: glucose, amino acids, etc
- water absorption in the large intestine

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12
Q

state and explain the factors that affect the diffusion rate of molecules into and out of cells (6)

A

surface area (max 2 marks):
- large surface area increases the chances of diffusion
- large surface area allows for more molecules to come into contact with the membrane
concentration gradient (max 2 marks):
- steeper concentration gradient results in a higher diffusion rate
- as molecules move from an area of high concentration to an area of low concentration
thickness of the membrane (max 2 marks):
- a thinner membrane allows for faster diffusion
- as molecules have a shorter distance to travel

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13
Q

what is osmosis (3)

A
  • movement of water molecules
  • across a partially permeable membrane
  • from a region of high water concentration to a region of low water concentration (or down a concentration gradient of water)
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14
Q

what is meant by a partially permeable membrane (1)

A
  • membrane that allows certain substances or molecules to pass through, but not others
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15
Q

(4)

A
  • water enters both cells by osmosis
  • plant cell has a cell wall
  • cell wall stops the plant cell from bursting
  • red blood cell has no cell wall
  • red blood cell swells and bursts
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16
Q

describe at least three adaptations of the lungs that help to make them efficient at exchanging gas by diffusion, explain how those adaptations aid the efficient exchange of gases via diffusion (6)

A
  • many alveoli
  • provide a large surface area to volume ratio
    _
  • alveoli walls are thin
  • provide a short diffusion path for O2 and CO2
    _
  • large capillary network around alveoli
  • capillary network removes oxygenated blood quickly
  • capillary network brings carbon dioxide to the lungs quickly
  • capillary network maintains a concentration gradient
17
Q

why did the student blot the potato cylinders dry when he removed them from the sugar solutions (2)

A
  • to remove excess liquid from the potato surface
  • excess liquid would make the potato weigh more
18
Q

why did the student calculate the percentage change in mass (1)

A
  • to allow results to be compared
  • because they had different masses at the start
19
Q

use the table and the graph to explain what happens to potato cells when they are placed in increasing sugar concentrations (4)

A
  • the percentage change in mass of the potato pieces decreases as the concentration of sugar increases (or the mass of the potato decreases as the concentration of sugar increases)
  • from 0.0 to 0.4 mol/dm3 the water concentration inside the potato is lower than outside
  • from 0.0 to 0.4 mol/dm3 water moves into the cells
  • from 0.6 to 0.8 mol/dm3 the water concentration outside the potato is lower than inside
  • from 0.6 to 0.8 mol/dm3 water moves out of the cells
  • water movement happens by osmosis
20
Q

when each side of a membrane has equal sugar concentrations, the solution is said to be isotonic, water molecules will be equally likely to move in both directions across the membrane, and therefore the net movement is zero, what is the isotonic point of this potato (1)

A
  • concentration where the line of best fit crosses the x-axis
  • any value between 0.5-0.6 mol/dm3
21
Q

suggest why root hair cells have large numbers of mitochondria (2)

A
  • mitochondria are the sites of aerobic respiration
  • mitochondria release energy
  • energy is necessary for active transport
22
Q

suggest why it is necessary to have large numbers of villi in the digestive system (2)

A
  • increases the surface area
  • allows for more absorption of nutrients
23
Q

give two products of digestion that are taken up by the villi into the blood stream (2)

A
  • amino acids
  • sugars
  • fatty acids
  • minerals
24
Q
A
25
Q

give an example of active transport

A
  • uptake of glucose by epithelial cells in the villi of the small intestine
  • uptake of ions from soil by root hair cells in plants
26
Q

plants need phosphate ions in order to make proteins, a plant is growing in soil flooded with water, explain why the plant cannot absorb enough phosphate ions (3)

A
  • nitrate ions are absorbed by active transport
  • active transport requires energy from respiration
  • respiration requires oxygen
  • no oxygen in water-logged soil
27
Q

give two ways a plant root is adapted for the absorption of water and minerals (4)

A
  • plant roots have root hairs
    _
  • root hairs are are very long
  • which gives them a large surface area
  • to increase the rate of absorption of water (and dissolved substances)
    _
  • root hairs have thin walls
  • thin walls allow the movement of water and dissolved substances
    _
  • root hair cells contain many mitochondria
  • (mitochondria) release energy through respiration
  • energy is used for active transport
28
Q

(6)

A

adaptations present in both:
- have a large surface area
- have many capillaries
- capillaries maintain concentration gradient
- both have thin walls
- thin walls provide a short diffusion distance for molecules to travel
adaptations of villi:
- have many mitochondria
- mitochondria provide energy for active transport of food molecules
- large SA increases the number of proteins in the membrane to allow more active transport to take place
adaptations of alveoli:
- alveolar walls are moist (which allows substances to diffuse faster)

29
Q

explain why a bacterium like E. coli can rely on diffusion for gas exchange, but humans need a respiratory system (2)

A
  • humans have a smaller surface area to volume ratio than a bacterium
  • diffusion distance is larger in humans
  • diffusion would not supply enough oxygen for the volume
30
Q

digested food molecules are absorbed into the blood in the small intestine, some of the food molecules are absorbed by active transport, explain why the rate of absorption of these molecules depends on the concentration of oxygen in the cells that line the small intestine (3)

A
  • active transport requires energy
  • as the movement of particles happens against concentration gradient
  • energy is provided by respiration
  • respiration requires oxygen
  • a higher concentration of oxygen allows a faster rate of respiration
31
Q

which part of the blood transports glucose

A

plasma

32
Q

name a chemical used to test for glucose

A

benedicts

33
Q

describe a test that could be used to show a persons urine contains glucose (2)

A
  • add benedicts reagent to urine and boil
  • positive result would turn blue to brick red
34
Q

explain how diabetes can cause the body cells to lose more water (2)

A
  • blood more concentrated (less dilute)
  • so more water moves out of cells by osmosis
  • water moves through a partially permeable membrane
35
Q

describe how the small intestine is adapted for efficient absorption (5)

A
  • villi provide large surface area
  • cappilaries one cell thick for short diffusion distance
  • small instestine long to increase time for absorption
  • good blood supply to maintain concentration gradient
  • cells have mitochondria for aerobic respiration for active transport
36
Q

amylase is a polymer of smaller molecules, name the molecule

A

amino acids

37
Q

name three parts of the human digestive system that produce amylase

A
  • mouth
  • pancreas
  • small intestine
38
Q

explain how amylase breaks dow starch, answer in terms of lock and key theory (3)

A
  • amylase enzyme has a complimentary substrate which binds to the active site of amylase
  • amylase and starch bind to form enzyme substrate complex
  • these react to form enzyme and products, maltose
39
Q

why did the student leave the starch and amylase solutions in the 5’C solution for 5 minutes before mixing them

A

so they could become the same temperature as the water

biology (paper one) (15 decks)

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