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Edexcel Gcse Biology > Paper 1 - Topic 1, Key Concepts In Biology > Flashcards

Paper 1 - Topic 1, Key Concepts In Biology Flashcards

1
Q

What is the acrosome

A

An organelle in the tip of a sperm that contains enzymes which digest the egg cell membrane

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2
Q

What is the active site

A

A specific region on an enzyme where the substrate binds and the reaction takes place

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3
Q

What is active transport

A

The movement of substances from a low concentration to a higher concentration across a membrane with the use of energy from respiration

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4
Q

What is Benedict’s test

A
  • used to test for reducing sugars (eg glucose)
  • colour change from blue to cloudy orange or brick red when heated
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5
Q

How do you test for reducing sugars

A
  1. Use Benedict’s solution
  2. Transfer 5cm3 of food sample to a test tube
  3. Prepare water bath to 75 degrees Celsius
  4. Add about 10 drops of Benedict’s solution to food sample
  5. Place in the water bath for 5 minutes with test tube holder
  6. Should turn to green, yellow or brick red if reducing sugars present (depends on concentration)
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6
Q

How do you test for carbohydrates

A
  1. Take 5cm3 of food sample
  2. Add few drops of iodine solution, should turn brown/orange
  3. Give a gentle shake and if starch/carbohydrates are present, colour will turn blue/black
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7
Q

What does the Biuret test, test for

A
  • test for proteins
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8
Q

How do you test for proteins

A
  1. Take 2cm3 of food sample in a test tube
  2. Add 2cm3 of biuret solution to food sample
  3. Should turn the sample blue
  4. Give a gentle shake
  5. Of sample does contain protein it will turn pink/purple colour
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9
Q

How do you test for lipids

A
  1. 5cm3 of food sample
  2. Add 2cm3 of Ethanol then shake vigorously
  3. Then add 2cm3 of distilled water
  4. If the solution goes a cloudy white colour, lipid is present
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10
Q

What is a carbohydrate

A

A large molecule that is synthesised into simple sugars

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11
Q

What are carbohydrases

A

Enzymes that break down carbohydrates into simple sugars

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12
Q

What is the cell membrane

A

A partially permeable barrier that surrounds the cell

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13
Q

What is the cell wall

A

An outer layer made of cellulose that strengthens the cell wall

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14
Q

What is a chloroplast

A

An organelle that is the site of photosynthesis

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15
Q

What is a chromosome

A

A long, coiled molecule of DNA that carries genetic information in the form of genes

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16
Q

What are cilia

A

Hair-like structures found on ciliated epithelial cells which waft substances across the surface of the tissue in one direction

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17
Q

What is a ciliated epithelial cell

A

A type of epithelial cell that lines the surface of structures such as the uterus and respiratory tract

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18
Q

What is the concentration gradient

A

The difference in concentration between two areas

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19
Q

What is denaturation

A

Upon exposure to high temperatures or extremes of pH, the permanent change in the shape of an enzymes active site that prevents the binding of the substrate

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20
Q

What is the definition for diffusion

A

The net spreading out of particles from a high concentration to a lower concentration

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21
Q

What is a diploid cell

A

A cell that contains two copies of each chromosome

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22
Q

What is an egg cell

A

A specialised female sex cell involved in reproduction

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23
Q

What is an electron microscope

A

A type of microscope that uses a beam of electrons to produce an image of a specimen, it has a greater magnification and resolution than a light microscope

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24
Q

What is an enzyme

A

A biological catalyst that increases the rate of reaction in living organisms

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25
Q

What is a eukaryotic cell

A

A type of cell found in plants and animals that contains a nucleus

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26
Q

What is a flagella (or flagellum)

A

A long hair-like structure found on bacterial cells that is used for cell movement

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27
Q

What is a haploid cell

A

A cell that contains a single copy of each chromosome (contains half the number of chromosomes)

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28
Q

What is a light microscope

A

A type of microscope that uses a series of lenses to magnify the visible light reflecting off of a specimen, it has a lower magnification and resolution than an electron microscope

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29
Q

What are lipases

A

Enzymes that break down lipids into fatty acids and glycerol

30
Q

What is a lipid

A

A large molecule that is synthesised from fatty acids and glycerol

31
Q

How do you work out the image size

A

Image size = magnification x real size

32
Q

What is magnification

A

The number of times bigger an image appears compared to the original object

33
Q

What is the mitochondria

A

An organelle that is the site of respiration

34
Q

What is the nucleus

A

Contains the genetic material of the cell and controls the activity of the cell

35
Q

What is osmosis

A

The diffusion of water molecules from a region of high water concentration to a region of lower water concentration across a partially permeable membrane

36
Q

What is a plasmid

A

Loops of DNA found in the cytoplasm of prokaryotic cells

37
Q

What are proteases

A

Enzymes that break down proteins into amino acids

38
Q

What is a protein

A

A large molecule that is synthesised from amino acids

39
Q

What is the rate of reaction

A

The speed at which reactants are turned into products

40
Q

What is the resolution

A

The smallest distance between two objects that can be distinguished

41
Q

What are ribosomes

A

Sub-cellular structures that are the site of protein synthesis

42
Q

What is a specialised cell

A

A cell that has a structure which makes it adapted to its function

43
Q

What is a sperm cell

A

A specialised male sex cell that is involved in reproduction

44
Q

What is the vacuole

A

An organelle found in plant cells which stores cell sap and supports the cell

45
Q

How do cells specialise

A

They undergo differentiation where the cell gains new sub-cellular structures in order for it to be suited to its role

46
Q

How are sperm cells specialised

A
  • specialised to carry the males DNA to the egg cell for successful reproduction
47
Q

How is a sperm cell adapted to its speciality

A
  • streamlined head and long tail to aid swimming
  • many mitochondria which supplies the energy to allow the cell to move
  • the acrosome has digestive enzymes which break down the outer layers of membrane of the egg cell
  • has a haploid nucleus, has 23 chromosomes
48
Q

How are egg cells specialised

A

Specialised to accept a single sperm cell and develop into an embryo

49
Q

How are egg cells specialised to their function

A
  • surrounded by a special cell membrane which can only accept one sperm and becomes i permeable after
  • lots of mitochondria to provide an energy source for developing embryo
  • large size and cytoplasm to allow quick, repeated division as embryo grows
50
Q

How are ciliated epithelial cells specialised

A

Specialised to waft bacteria (trapped by mucus) to the stomach

51
Q

How are ciliated epithelial cells specialised to their function

A
  • long, hair-like processes called cilia waft bacteria trapped by mucus down to the stomach, where they are killed by stomach acid
52
Q

Where is mucus produced

A

Goblet cells

53
Q

How are root hair cells specialised in plants

A

Specialised to take up water by osmosis and mineral ions by active transport from the soil as they are found in the tips of roots

54
Q

How are root hair cells in plants specialised to their function

A
  • have a large surface area, meaning more water can move in
  • the large permanent vacuole affects the speed of movement of water from the soil to the cell
  • mitochondria to provide energy from respiration for the active transport of mineral ions into the root hair cell
55
Q

How are xylem cells specialised in plants

A

Specialised to transport water and mineral ions up from the plant from roots to shoots

56
Q

How are xylem cells specialised to their functions in plants

A
  • when formed, lignin (a chemical) is deposited which causes the cells to die and they become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
  • lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water
57
Q

How are phloem cells specialised in plants

A

Specialised to carry the products of photosynthesis to all parts of the plant

58
Q

What are some of the features of a light microscope

A
  • Has two lenses
  • usually illuminated from beneath
  • approx magnification of 2000x
  • approx resolving power of 200nm
59
Q

What are light microscopes used to view

A
  • tissues, cells and large sub-cellular structures
60
Q

What can an electron microscope be used to view

A

Deep inside sub-cellular structures eg mitochondria, ribosomes and chloroplasts

61
Q

What are some of the features of an electron microscope

A
  • magnification of 2,000,000x
  • resolving power 10nm and 0.2nm
  • electrons are used instead of light as electrons have much smaller wavelengths than light waves
62
Q

How do you use a light microscope

A
  1. Place the slide on the stage and look through eyepiece lens
  2. Turn the focus wheel to obtain a clear image
  3. Start with the lowest objective lens magnification
  4. Increase the magnification of the objective lens and refocus
63
Q

How do you prepare a slide

A
  1. Take a thin layer of cells from sample by either peeling them off or using a cotton bud
  2. Add a small amount of chemical stain (used to make specimen look more visible)
  3. Apply the cells to glass slide by placing them of wiping cotton bud against it
  4. Carefully put a coverslip onto the slide and try not get air bubbles
64
Q

How do you work out actual size

A

Measured size / magnification

65
Q

How do you work out total magnification

A

Objective lens magnification x eyepiece lens magnification

66
Q

What happens to the rate of reaction of enzymes when the temperature is above their optimum

A

Rate of reaction decreases rapidly and eventually reaction will stop, the temp is too hot and the bonds that hold the enzyme together will break and this changes the shape of the active site and substrate can’t fit into active site

67
Q

How do you work out the rate

A

Change (change in the substance being measured) / time

68
Q

How do you do the ‘osmosis in potatoes’ practical

A
  1. Cut potato into small discs of equal size (eg 2cm diameter)
  2. Blot potato disks gently with tissue paper to remove excess water
  3. Measure the initial mass of each disk
  4. Place the disks in sucrose solutions of different concentrations (eg 1%, 2%, 3% etc)
  5. Blot paper with tissue paper again and record new mass
  6. Work out difference in mass and use percentage change to work out the loss/gain in mass
69
Q

What is the independent variable of the ‘osmosis in potatoes’ experiment

A

Changing the concentration of the sucrose solution

70
Q

What is the dependent variable in the ‘osmosis in potatoes’ experiments

A

Measuring the change in mass of the potato disks

71
Q

What is the control variable of the ‘osmosis in potatoes’ experiment

A

The diameter of the potato disks

72
Q

What is happening in the ‘osmosis in potatoes’ experiment

A

Water is moving by osmosis from a more dilute solution in the potato, to a more concentrated solution (the sucrose solution) across a selectively permeable membrane

Edexcel Gcse Biology (9 decks)

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