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Biology Edexcel > 1 - Key Concepts > Flashcards

1 - Key Concepts Flashcards

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1
Q

Define eukaryotic cells

A

Complex cells (Animal and plant cells)

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2
Q

Define prokaryotic cells

A

Small, simple cells (Single-celled organisms. e.g. bacteria)

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3
Q

State the 5 organelles in an animal cell

A
  • Nucleus
  • Cytoplasm
  • Mitochondria
  • Cell Membrane
  • Ribosomes
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4
Q

Explain the purpose of the nucleus (2)

A
  • Contains genetic material that controls the activities of the cell.
  • Genetic material is arranged into chromosomes
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5
Q

Explain the purpose of Cytoplasm (2)

A
  • Gel like substance where most chemical reactions happen.
  • Contains enzymes that control these chemical reactions
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6
Q

Explain the purpose of Mitochondria (2)

A
  • Where most reactions for aerobic respiration take place
  • Respiration transfers energy that the cells needs to work
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7
Q

Explain the purpose of a Cell membrane (2)

A
  • Holds the cell together
  • Controls what goes in and out
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8
Q

Explain the purpose of Ribosomes

A
  • Tiny structures Involved in translation of genetic material in protein synthesis
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9
Q

State the 3 extra organelles plant cells have

A
  • Cell wall
  • Chloroplasts
  • Large Vacuole
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10
Q

Explain the purpose of the cell wall (2)

A
  • Made of cellulose
  • Supports and strengthens the cell
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11
Q

Explain the purpose of the chloroplasts (2)

A
  • Where photosynthesis occurs
  • Contains chlorophyll (green substance)
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12
Q

Explain the purpose of the large vacuole (2)

A
  • Contains cell sap, a weak solution of sugar and salts
  • Maintains the internal pressure to support the cell
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13
Q

State the 5 organelles in a bacteria cell

A
  • Chromosomal DNA
  • Plasmid DNA
  • Ribosomes
  • Cell membrane
  • Flagellum
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14
Q

Explain the purpose of Chromosomal DNA (3)

A
  • One long circular chromosome
  • Controls the cells activities and replication
  • Floats free in the cytoplasm (NOT in nucleus)
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15
Q

Explain the purpose of Plasmid DNA

A
  • Small loops of extra DNA that isn’t part of the chromosome
  • Contains genes for things like drug resistance which can be passed between bacteria
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16
Q

Explain the purpose of the Flagellum (2)

A
  • A long, hair like structure that rotates to make the bacteria move
  • Used to move away from harmful substances and towards beneficial things like nutrients/oxygen
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17
Q

Define specialised cells

A

Cells that have adapted to their function

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18
Q

Define and explain the importance of a haploid nucleus

A
  • When a nucleus only contains half the number of chromosomes that is in a normal body cell
  • Means when an egg and sperm nucleus combine at fertilisation, the resulting cell will have the right number of chromosomes
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19
Q

Define and explain the importance of a haploid nucleus

A
  • When a nucleus only contains half the number of chromosomes that is in a normal body cell
  • Means when an egg and sperm nucleus combine at fertilisation, the resulting cell will have the right number of chromosomes
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20
Q

Explain how egg cells are specialised to their purpose (3)

A
  • Contains nutrients in the cytoplasm to feed the embryo
  • Has a haploid nucleus
  • Straight after fertilisation, membrane changes structure to stop sperm from getting in
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21
Q

Explain how sperm cells are specialised to their purpose (4)

A
  • Has a long tail so it can swim to the egg
  • Has lots of mitochondria in the middle section to provide energy needed to swim the distance
  • Has an acrosome at the front of the head where it stores enzymes needed to digest through the membrane of the egg cell
  • Haploid nucleus
22
Q

Explain how Ciliated Epithelial Cells are specialised for moving materials

A
  • Epithelial cells line the surfaces of organs
  • Some of them have cilia on the top surface of the cell
  • To move substances, cilia beat in one direction along the surface of the tissue
23
Q

Give an example on how Ciliated Epithelial cells are specialised for moving materials

A
  • The lining of the airways contains lots of Ciliated Epithelial cells
  • These help move mucus up to the throat so it can be swallowed and doesn’t reach the lungs
24
Q

Why are electron microscopes better than light microscopes? (2)

A
  • Electron microscopes use electrons rather than light
  • They have higher magnification and resolution, so you can see smaller things in more detail like internal structure
25
Q

Why are microscopes used? (2)

A

To magnify and increase resolution of an image

26
Q

Explain how to prepare a specimen to be viewed under a light microscope (4)

A

1) Take a thin specimen slice so that light can pass through it

2) Take a clean slide and use a pipette to place a drop of water in the middle, which will secure the specimen in place. Put your specimen on the slide

3) Add a drop of stain to transparent specimens to make it easier to see

4) Place a Cover Slip on one end and lower it down onto the slide, pressing gently so no air bubbles are trapped.

27
Q

State the equation for magnification

A

Magnification = image size
———————–
real size

28
Q

Define Catalyst

A

A substance that increases the speed of a reaction without being changed or used up.

29
Q

Explain the lock and key hypothesis for enzymes (5)

A

1) Enzymes are biological catalysts. The substrate is the molecule changed in the reaction

2) Every enzyme has an active site, which joins onto its substrate to catalyse a reaction

3) Enzymes usually only work with one substrate

4) This is because the substrate has to fit into the active site for the enzyme to work. If the substrate doesn’t match, the reaction won’t be catalysed.

5) Called lock and key because the substrate fits into the enzyme like a key fits in a lock

30
Q

Explain how temperature affects the rate of an enzyme-catalysed reaction (3)

A
  • Higher temperature increases the rate
  • Until the temperature gets too high and some of the bonds holding the enzyme together break
  • This also changes the shape of the active site, so the substrate won’t fit anymore. The enzyme is now denatured
31
Q

Explain how pH affects enzyme-catalysed reactions (3)

A
  • If the pH is too high of low, it interferes with the bonds holding the enzyme together
  • This changes the shape of the active site and denatures the enzyme
  • MOST enzymes work best at pH 7
32
Q

What is the optimum pH for pepsin?

A

pH 2 (acidic)

33
Q

Explain how Substrate concentration affects enzyme-catalysed reactions (3)

A
  • The higher the substrate concentration, the faster the reaction
  • Because it is more likely that the enzyme will meet and react with a substrate molecule
  • Only true up to a point as eventually all active sites will be full as there are so many substrate molecules
34
Q

Which enzyme catalyses the breakdown of starch to maltose?

A

Amylase

35
Q

If starch is present, what colour will iodine solution turn?

A

From browny-orange to blue-black

36
Q

Describe the practical to investigate how pH affects amylase activity

A

1) Drop of iodine solution in each well of a spotting tile
2) Heat a beaker of water over a bunsen until it’s 35* - keep temp constant
3) Add 3cm^3 of amylase solution and 1cm^3 of a buffer solution

37
Q

Describe the practical to investigate how pH affects amylase activity (8)

A

1) Drop of iodine solution in each well of a spotting tile

2) Heat a beaker of water over a bunsen until it’s 35* - keep temp constant

3) Add 3cm of amylase solution and 1cm of a buffer solution (pH 5) to a boiling tube

4) Place tube in the beaker for 5 mins

5) Mix the starch solution into the boiling tube and start a stop clock

6) Use continuous sampling to record how long it takes for amylase to break down all the starch

7) By using a pipette to take a sample from the boiling tube every 10 secs and drop it into the well

8) when iodine solution remains browny-orange, starch is no longer present

38
Q

Define a buffer solution

A

A solution that can resist pH change upon the addition of an acidic or basic components

39
Q

State the equation to calculate rate of reaction

A

Rate = 1000/amt that has changed
———
time

40
Q

Give an example of how plants use enzymes (3)

A

1) Plants store energy in the form of starch

2) When plants need energy, enzymes break down the starch into smaller molecules (sugars)

3) These can then be respired to transfer energy to be used by the cells

41
Q

Give an example of how humans use enzymes (2)

A

1) Most food molecules are too big to pass through the walls of the digestive system

2) So digestive enzymes break them down -> smaller, soluble molecules

Which can pass easily through walls of digestive system and absorbed into blood stream

42
Q

Enzymes called _______ convert carbohydrates into simple sugars

Give an example of _______

A

Enzymes called CARBOHYDRASES convert carbohydrates into simple sugars

e.g. amylase

43
Q

Enzymes called _______ convert proteins into amino acids

A

Enzymes called PROTEASES convert proteins into amino acids

44
Q

Enzymes called _______ convert lipids into glycerol and fatty acids

A

Enzymes called LIPASES convert lipids into glycerol and fatty acids

45
Q

Describe the practical to test for Sugars

A

1) Add Benedict’s reagent (blue) to a sample and heat in a water bath set to 75*C

2) If sugars are present, it will form a coloured precipitate

3) The higher the concentration of reducing suar, the further the colour change goes.

(Low conc.) (High conc.)
Blue->Green->Yellow->Orange->Brick Red

46
Q

Describe the practical to test for Proteins

A

Biuret test

1) Add drops of potassium hydroxide to make solution alkaline

2) Then add some copper(II)sulfate solution (bright blue)

  • If NO protein is present, solution stays BLUE
  • If protein IS present, solution turns PURPLE
47
Q

c

A

Emulsion test

1) Shake test substance with ethanol until it dissolves, pour into water

If lipids are PRESENT, they will precipitate out the liquid as a milky emulsion

The more liquid there is, the more ntoiceable the milky colour is

48
Q

Describe the practical to test for Lipids

A

Emulsion test

1) Shake test substance with ethanol until it dissolves, pour into water

If lipids are PRESENT, they will precipitate out the liquid as a milky emulsion

The more liquid there is, the more ntoiceable the milky colour is

49
Q

Describe the practical to test for Iodine

A

1) Add iodine solution to the test sample

  • If starch is PRESENT, sample changes from browny-orange to BLUE-BLACK
  • If NO starch is present, it stays BROWNY-ORANGE
50
Q

Describe the practical to see how much energy a food contains (calorimetry) (7)

A

1) Weigh and skewer the food on a mounted needle

2) Add a set volume of water to a boiling tube

3) Measure temp of water then set fire to food using a bunsen

4) Immediately hold burning food under boiling tube until it goes out, then relight and repeat until it won’t catch fire again

5) Measure temp of water

6) Energy in food (J) = Water (g) x Temp change (*C) x 4.2

7) Energy per gram of food (J/g) = energy in food / Mass of food (g)

Biology Edexcel (9 decks)

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