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Alevel Biology > Mocks > Flashcards

Mocks Flashcards

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1
Q

Structure of cell surface membrane?

A

Bilayer of phospholipids with hydrophobic tails in contact with, regulates transport of materials entering and exiting

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2
Q

Structure of nucleus?

A

Genetic material stored
Nuclear envelope, nuclear pores

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3
Q

Structure of mitochondria?

A

Energy, ATP

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4
Q

Structure of chloroplasts?

A

Thylakoids stacked to make stroma

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5
Q

Structure of Golgi apparatus

A

Stack of flattened cisternae and associated vesicles

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6
Q

Structure of lysosomes s

A

Sphere shaped sacs filled with hydrologic enzymes

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7
Q

Structure of ribosomes

A

RNA protein complexes
Site of protein synthesis

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8
Q

Structure of rough and smooth endoplasmic reticulum

A

One has ribosomes one does not

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9
Q

Structure of cell wall

A

Cellulose: plant
Murin:
Chitin

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10
Q

Structure of cell vacuole

A

Membrane sacs
Store water and nutrients

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11
Q

What is a tissue?
Organ
Organ system

A
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12
Q

How do prokaryotic cells differ from eukaryotic cells?

A

They are smaller
Cytoplasm lacks membrane bound organelles
Smaller ribosomes (70s)
No nucleus
Cell wall of Murein

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13
Q

Features of prokaryotic cells?

A

Has a slime capsule
Has one or more flagella for movement
Plasmids instead of nucleus

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14
Q

What are viruses?

A

Acellular and non-living

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15
Q

What do virus particles include?

A

Genetic material
Capsid
Attachment protein

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16
Q

Principles and limitations of optical microscope?

A

Light microscope, longwave length so low resolution
Can be in colour
Can be living

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17
Q

Principles and limitations of transmission electron microscopes?

A

Highest resolution due to short wavelength
Sample has to be thin
Complicated staining process

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18
Q

Principles and limitations of scanning electron microscopes?

A

High resolution due to short wavelength
Can produce 3D images
Lower resolution than transmission

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19
Q

What is magnification?

A

How many times bigger the image of the specimen observed is compared to the real life specimen

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20
Q

What is resolution?

A

The smallest distance between 2 objects where they can still be seen separately

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21
Q

How do you work out magnification?

A

Size of image/ size of real object

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22
Q

Centrifugation?

A

First you blend your cell in a cold buffered isotonic solution
Then you filter
Place in a centrifuge and spin at a slow speed, remove the nuclei but respin the supernatant at a faster speed, ribosomes need to be spun the fastest

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23
Q

How did the scientific community previously distinguish between artefacts and cell organelles?

A

If they saw an object in a specimen prepared using one preparation technique but not another it was likely to be an artefact

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24
Q

Can all cells divide?

A

No, some lose the ability to when they become adult

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25
Q

What is the order of the cell cycle?

A

Interphase, prephase, metaphase, anaphase, telephase

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26
Q

When does DNA replication occur?

A

Interphase

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27
Q

What happens in mitosis?

A

Eukaryotic cell divides to produce 2 identical daughter cells

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28
Q

Behaviour of chromosomes in interphase, prophase, metaphase, anaphase and telophase of mitosis?

A

Interphase: chromatid condense
Prophase: chromosomes highly condensed and centrosomes begin to separate
Metaphase: chromosomes line up along equator , nucleus dissolves
Anaphase: chromosomes move to oppo’site poles
Telophase: chromosomes decondense and nuclear envelope reforms around 2 daughter nuclei

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29
Q

Why are spindle fibres attached to centromeres in separation of chromatids?

A

So they can contract to pull the chromatids to opposite poles

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30
Q

What’s it called when the cytoplasm divides to produce 2 new cells

A

Cytokinesis

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31
Q

What does uncontrolled cell division lead to?

A

Tumours and cancers

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32
Q

How does binary fission in prokaryotic cells occur?

A

Circular DNA and plasmids replicate
Cytoplasm divides
2 daughter cells produced

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33
Q

Why don’t viruses undergo cell division?

A

They are non-living

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34
Q

How do you prepare stained squashes of cells from plant root tips?

A

Cut 2cm of root tip
Place in a test tube of hydrochloric acid inside a heated water bath
Leave for 5 minutes
Remove and wash off hydrochloric acid
Tease the root tip open on a slide and drop 1 drop of dye
Leave for 2 minutes before placing cover slip on top

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35
Q

What is DNA and what does RNA do?

A

DNA stores genetic information and RNA takes this genetic information to the ribosomes

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36
Q

What is the structure of DNA and RNA?

A

DNA: deoxyribose, phosphate, adenine, thymine, cytosine, guanine
RNA: ribose, phosphate, adenine, uracil, cytosine, guanine

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37
Q

What’s a condensation reaction?

A

A reaction where a bond is made between 2 molecules, a molecule of water is produced

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38
Q

Bond that forms between 2 nucleotides?

A

Phosphodiester

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39
Q

Structure of DNA vs RNA?

A

DNA: helix, long, hydrogen bonds, 2 polynucleotide chains
RNA: short polynucleotide chain

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40
Q

Why did scientists doubt that DNA carried the genetic code?

A

Because it was too simple

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41
Q

what does semi-conservative replication of DNA ensure?

A

Genetic continuity between generations of cells

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42
Q

Process of semi-conservative replication?

A

The double helix unwinds due to DNA helicase breaking the hydrogen bonds between complementary bases
There are now exposed bases which attract new DNA nucleotides to the template strand
DNA polyermase in a condensation reaction joins adjacent complementary nucleotides

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43
Q

What did Watson and cric do?

A

Bacteria grown in broth containing nitrogen 15 so it now had DNA containing heavier nitrogen
DNA settled at bottom of centrifuge
Bacteria with DNA containing heavier nitrogen allowed to replicate in broth containing only light nitrogen
Was a settle in the middle of heavier abdominal lighter nitrogen

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44
Q

What makes up ATP?

A

ADP + Pi during photosynthesis or respiration
Adenine, ribose and 3 phosphate groups

45
Q

Properties of water?

A

Metabolite for many metabolic reactions
Solvent where metabolic reactions occur
High heat capacity so buffers changes in temperature
High latent heat of vaporisation, cooling effect

46
Q

Where do inorganic ions occur?

A

In solution in the cytoplasm and body fluids of organisms

47
Q

What is a genome?

A

Full set of genes in a cell

48
Q

Whatt is a proteome?

A

Full range of proteins that a cell is able to produce

49
Q

Structure of mRNA?

A

Long single stranded molecule
Nucleotides attached by phosphodiester bonds
Contains adenine guanine cytosine and uracil

50
Q

Structure of tRNA?

A

Clover shaped
Amino acid binding site
Anti codon

51
Q

What does transcription produce in prokayrotes and eukaryotes?

A

Prokaryotes: mRNA from DNA
Eukaryotes: pre mRNA then spliced into mRNA

52
Q

What happens during translation?

A

In cytoplasm mRNA attaches to a ribosome
Each tRNA has the complementary anticodon to the codon on the mRNA
First tRNA carries methionine , forms hydrogen bonds with start codon on mRNA
Second tRNA bonds with next codon
Ribosome moves along mRNA in 5 to 3 reading next codon

53
Q

What is hydrolysis?

A

The breaking of a bond using a water molecule

54
Q

Common monosaccharides?

A

Glucose, galactose, fructose

55
Q

What bond is formed in a condensation reaction between 2 monosaccharides?

A

Glycosidic bond

56
Q

Maltose make up?

A

Glucose + glucose

57
Q

Sucrose make up?

A

Fructose + glucose

58
Q

Lactose make up?

A

Glucose + galactose

59
Q

2 isomers of glucose?

A

Alpha glucose: h on top

Beta glucose: h on bottom

60
Q

How many triplets and amino acids are there?

A

20 amino acids: 60 triplets

61
Q

Are glycogen, starch, cellulose formed from beta or alpha glucose

A

Glycogen and starch: alpha
Cellulose: beta

62
Q

Glycogen structure and function

A

Branched chains
Alpha glucose
1-4 glycosidic bonds
Branching: very efficient storage and release of glucose

63
Q

Starch structure and function?

A

Amylose: unbranched , forms coil so compact and good storage
Amylopectin: branched , has 1-6 glycosidic bonds , large SA so glucose released quickly

Starch general in plants: used to store excess glucose as its too large to leave cells and insoluble so won’t effect water potential

64
Q

Cellulose structure and function?

A

Straight chains that layer on top of each other with hydrogen bonds making it very strong, microfibrils form , 1-4 glycosidic bonds
Provides structure for cell wall, allows cell to become turgid

65
Q

Which out of cellulose, starch and glycogen are in plant or animal cells?

A

Cellulose, starch: plant
Glycogen: animal

66
Q

Reducing and non reducing sugars test?

A

Reducing: add Benedict’s to sample, heat, turns from blue to yellow, green, brick red
No reducing: negative reducing test, boil with acid, neutralise, add Benedict’s and heat, turns from blue to brick red

67
Q

Test for starch?

A

Add iodine to sample
Turns from orange to blue black

68
Q

Triglyceride structure?

A

Condensation of 1 molecule of glycerol and 3 fatty acids

69
Q

What bond forms between a condensation reaction between glycerol and a fatty acid ?

A

Ester bond

70
Q

Saturated vs unsaturated ?

A

Saturated has no double carbon to carbon bonds whereas unsaturated does

71
Q

Different properties of triglycerides and phospholipids related to their structure?

A

Triglycerides: insoluble in water , effective storage
Phospholipids: help metabolism

72
Q

Lipids test?

A

Add distilled water and ethanol, shake, white emulsion forms

73
Q

Amino acid general structure?

A

NH2 - CRH- C=O-co

74
Q

Condensation reactions between 2 amino acids forms?

A

Peptide bond

75
Q

What does a functional protein contain?

A

1 or more polypeptides

76
Q

Hydrogen bonds?
Ionic bonds?
Disulfide bridges?

A

Hydrogen bonds: lots of them easily breakable
Ionic bonds: typically strong , attract charged ions
Disulfide bridges: 2 sulfur atoms of cysteine very strong

77
Q

Primary?
Secondary?
Tertiary?
Quaternary?

A

Primary: chain of amino acids:
Secondary: folding of beta pleated sheets or alpha helix with hydrogen bonds?
Tertiary: further folding to unique 3D structure
Quaternary:

78
Q

Protein biuret test?

A

Add sodium hydroxide and copper sulfate
Turns from blue to purple

79
Q

What do enzymes do?

A

Lower activation energy

80
Q

Induced fit model?

A

The active site and substrate are complementary but the active site can slightly change shape for a perfect fit, this forms enzyme substrate complexes

81
Q

Enzyme specificity described?

A

If enzymes are not specific they cannot bind, meaning they cannot form enzyme substrate complexes

82
Q

Effect of enzyme concentration
Substrate concentration
Concentration of competitive and non-competitive inhibitors
Ph
Temperature
On rate of reaction?

A

Enzyme concentration: peak then plateau as becomes limiting factor
Substrate concentration: peak then plateau as becomes limiting factor
Non-comp: if increased then rate of reaction decreases as active site changes shape
Competitive: if conc increases rate of reaction decreases
Ph: before or after optimum rate stays low
Temperature: if increases rate of reaction increases until after optimum where denaturing occurs

83
Q

How have models of enzyme action changed over time?

A

Lock and key method is not right as active site slightly changes shape like seen in the induced fit model

84
Q

What is the fluid-mosaic model?

A

Arrangement of the bi-layer of phospholipids, integrated proteins, glycogproteins and glycolilipds

85
Q

What does the phospholipids bilayer do?

A

Form a barrier to dissolved substances
Centre is hydrophobic so doesn’t allow water soluble substrances through but does allow small, non-polar through

86
Q

What do the intrinsic proteins do?

A

Channel proteins and carrier proteins allow large molecules, polar molecules and ions to pass through membranes

87
Q

What do peripheral proteins do?

A

Act as receptors and allow cell to detect chemicals released from other cells so they can respond

88
Q

What are glycoproteins?

A

Proteins with carbohydrates attached to

89
Q

What are glycolipids?

A

Lipids with carbohydrates attached to

90
Q

What does cholesterol do?

A

Fits between phosophlipids
Restricts movement in membrane to give stability by binding tails of phospholipids making them back together closer
Makes membrane less rigid
Hydrophobic region so act as barrier to polar substances

91
Q

What happens to the membrane as tempterature increases?

A

Phopslipids have more kinetic energy, belayer less gel-like and more fluid

92
Q

How do you investigate membrane permeability?

A

Use a beetroot
Pigments can’t pass through membrane but leak out when it’s cooked
High temp increase membrane fluidity and cause pigment to break out of cell

93
Q

What is a colourimeter?

A

Passes light of specific wavelengths through a liquid and measures how much light is absorbed , use opposite colour

94
Q

How do you determine concentration using a colourimeter?

A

Several sample solutions of known conc are prepared and tested
Conc are plotted on graph against absorbance
Generates a calibration curve
Unknown sampler results compared to known sample

95
Q

What is diffusion?

A

Movement of molecules or ions from area of high to low concentration , passive process

96
Q

What affects simple diffusion?

A

Concentration gradient, membrane thickness, surface area ,temperature

97
Q

What is facilitated diffusion?

A

Large molecules and charged particles move very slow through membrane so need to diffuse through carrier or channel proteins

98
Q

Carrier proteins?

A

Move large molecules
Large molecules attach
Protein changes shape releasing molecule on other side of membrane

99
Q

Channel proteins?

A

Forms pores for charged particles
No changing shape just a simple tunnel

100
Q

What affects facilitated diffusion?

A

Conc gradient, greater- faster rate
Number of channel or carrier proteins; more = faster

101
Q

What is osmosis?

A

Diffusion of water molecules across a partially permeable membrane, movement of water from high to low water potential

102
Q

What is water potential?

A

Likelihood of water molecules diffusing out of or into a solution

103
Q

Animal cells osmosis?

A

Can be lysed: too much pressure, high water portneital outside vs inside
Can be normal: no net water movement
Can be shrivelled: water potential lower outside than inside so moves out

104
Q

Plant cells osmosis?

A

Can be turgid: normal, cell wall protects from bursting, water potential higher outside so travels in
Flaccid: no net water movement
Plasmolyzed: vacuoles shrink and cell membrane pull away from cell wall water potential higher inside than out

105
Q

Active transport?

A

Active, move across a membrane from area of low to high concentration against a concentration gradient, requires ATP

106
Q

What is used in active transport?

A

Carrier proteins but because they have to go from low to high, ATP is used , hydrolysed in ADP and pi which releases energy so it can be transported

107
Q

Co- transport?

A

Uses carrier proteins called co-transporters, bind to 2 molecules at a time. 1 moves down conc gradient and this is used to move other across membrane against conc gradient

108
Q

Co-transport of glucose in small intestine?

A

Sodium ions actively transported out of epithelial cells into the blood by sodium-potassium pump
This creates conc gradient( more sodium in lumen of ileum than inside epithelial cell
2.) conc gradient causes NA ions to diffuse from lumen in epithelial cell down conc gradient
Na glucose cotransproter protein helps
Glucose enters with sodium
Higher concentration of glucose inside epithelial cell than in blood so glucose diffuses into blood down conc gradient through protein channel by facilitated diffusion

109
Q

What affects rate of active transport?

A

Speed of carrier proteins
Number of carrier proteins
Rate of respiration

Alevel Biology (3 decks)

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