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Ocr Gcse Biology > B1 > Flashcards

B1 Flashcards

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1
Q

What are the sizes od eukaryotic and prokaryotic cells ?

A
  • Eukaryotic range from 10 micrometers to 100 micrometeres

- Prokaryotic range from 1 micrometer to 10 micrometeres

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2
Q

Which cells are more complex, eukaryotic or prokaryotic cells and what organisms do they make up?

A

Eukaryotic cells are more complex cells making up animal and plant cells
-Prokaryotic cells are simple cells mkaing up bacteria cells

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3
Q

What are the main structures in plant and animal cells?

A 
Animal cells contain:
-Nucleus
-Cell membrane
-Cytoplasm
-Mitochondria
Plant cells contian:
-All of the above
-Cell wall
-Vacuole
-Chloroplast
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4
Q

What are bacteria?

A
  • The smallest living organisms
  • Unicellular
  • Usually 1 micrometer
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5
Q

Prokaryotes examples?

A
  • E. coli - Causes food poisoning
  • Streptococcus - Causes sore throats
  • Streptomyces - found in cells, antibiotic created from them
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6
Q

What are the main stuctures of bacteria cells and their uses?

A

Main structures include:

  • Chromosomal DNA - One long circular chromosome that controls cell activity, free floating
  • Plasmids - Small extra loop of DNA,not part of chromosme. Antibiotic reistance
  • Cell membrane - Control what goes in and out of cell
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7
Q

What are the other stuctures of bacteria cells and their uses?

A
  • Flagella - Long tail like, helps movement through liquid
  • Pili - Tiny, hairlike structures, enable attatching to structures, can transfer genetic material
  • Slime capsule - Slime layer out of cell,stops drying out
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8
Q

Why do scientists stain cells?

A

Becuase some stains stain specific sub-cellular structures making them easy identify

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9
Q

What are some common stains and their uses?

A
  • Methylene blue- Makes is easier to see nucleus of animal cells
  • Iodine makes it easier to see plant cell nucleus
  • Crystal violet - Stains bacteria cells wall
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10
Q

Whats total magnification using lens magnification formula?

A

Total mag = eyepiece lens mag * objective lens mag

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11
Q

Whats formula for magnification using image and real size?

A

magnification = image size / real size

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12
Q

What are the 2 types of electron microscopes and their uses?

A
  • Transmission electron microscope - produce most magnified images, work in similar way to light microscopes, beams of electrons pass through sample and focuses making an image
  • Scanning electron microscope - Makes 3D image of a surface. Beam of electrons sent across specimin surface and reflect making an imag
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13
Q

What are the advantages and disadvantages to the electron microscope?

A 
Disadvantages:
- Expensive to buy and operate
- Large and difficult to move
- Sample prep is complex
- B&W images, false colour can be added
- Specimens are dead
- Large and hard to move
Advantages:
- Resolution up to 0.1nm
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14
Q

What are the advantages and disadvantage to the light microscope?

A 
Advantage:
- Cheap to buy and operate
- Small and portable
- Simple to prep a sample
- Natural colour of specimen seen, unless stain is used
- Specimens can be dead or alive
Disadvantage:
- Resolution only up to o.2 micrometer
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15
Q

What does DNA contain?

A
  • All of an organism’s genetic material - the chemical instructions it needs to grow an develop
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16
Q

How is DNA arranged/

A

Into chromosomes

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17
Q

What are chromosomes?

A
  • Long molcecules of coiled up DNA
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18
Q

What are genes?

A
  • Short sections of DNA that code for a characteristic, eye colour
  • The code a gene contains causes specific proteins to be made, these particular proteins determine the cells function
  • E.g: Protein haemoglobin found in red blood cells. Binds to O2, red blood cells transport this round body
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19
Q

What controls how an organism functions and how it looks?

A
  • The combination of genes

- E.g genes determine blood group, freckles or dimples

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20
Q

What is the shape of DNA?

A
  • Double helix, double strand spiral
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21
Q

What is a single strand of DNA made up of?

A
  • Lots of nucleotides joined in a long chain

- This makes DNA a polymer

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22
Q

What does each nucleotide contain?

A
  • A deoxyribose sugar, phosphate group and a base

- Arranged in phosphate-sugar-base

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23
Q

What do all nucleotides in DNA have in common?

A
  • They have the same sugar and phosphate group
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24
Q

What do bases in DNA do?

A
  • They form cross links with the bases from the other strand

- This keeps both strands tightly wound together

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25
Q

What is complementary base pairing?

A

A-T. adenine-thymine

C-G cytosine-guanine

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26
Q

What are polymers?

A
  • Polymers are large complex molecules composed of long chains of monomers joined together
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27
Q

What are monomers?

A
  • Small basic molecular units
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28
Q

How is DNA a polymer?

A
  • It is made up of nucleotide monomers
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29
Q

Why is a copy of DNA made in protein synthesis?

A
  • The DNA is too big to leave the nucleus of the cell and enter the cytoplasm
  • So copy DNA is made, a single strand mRNA
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30
Q

What is the process in which mRNA is produced?

A
  • Transcription
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31
Q

What happens in transcription(mRNA production)?

A
  • DNA around a gene unzips, both strands seperated
  • One of the strands acts as a template
  • Complementary bases attach to strand being copied
  • No thymine in mRNA, uracil binds with adenine
    mRNA detatches from DNA
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32
Q

What happens after mRNA is produced?

A
  • Its small enough, so it moves out of nucleus

- Travels to subcellular structure, ribosomes in cytoplasm

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33
Q

What are the ribosomes?

A

A subcellular structture in which proteins are made

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34
Q

What is the process in which proteins are made known as?

A

Translation

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35
Q

What determines what proteins are produced?

A
  • Order of bases in a gene that decides order of amino acids in a protein
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36
Q

How does ribsosome make proteins ( in simple terms)?

A
  • mRNA attaches to a ribosome

- Nucleotide sequencce in interpreted and protein is made

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37
Q

Describe the whole process of translation?

A
  • Ribosomw reads mRNA nucelotides in codons or triplet codes, these all code for a specific amino acid
  • Ribosome keeps reading codon adding more amino aicds, which join to make a protein
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38
Q

What are enzymes?

A
  • Proteins that are biological catalysts, they speed up a reaction without being used up
39
Q

Instead of using enzymes why cant you just increase the temperature of the cell?

A
  • While increase in temp increases reaction rate, it can also increase the speed of unwanted reactions
  • If temp increases too much, it damage the cell
40
Q

What is an advantae to an enzyme?

A

-Decrease the need for high temps in the body

41
Q

What are 2 uses of biological enzymes?

A
  • Build larger molcules form smaller ones, protein synthesis

- Break down larger molecules into smaller ones, digestion

42
Q

Why are enzymes not all identical?

A
  • Each is a protein, made of long amino chians folded for a specific shape
  • Each enzyme has a different use
43
Q

What is the molecule that binds to an enzyme and where does it bind?

A
  • Substrate and it binds to the active site
44
Q

Why do enzymes not bind to all molecules?

A
  • Enymes are highly specific, so they can only bind to 1 type of substrate
  • SUbstrate must fit exactly in active site of the enzyme or molecule dosen’t bind
45
Q

What is the high specifity of an enzyme known as ?

A
  • The lock and key hypothesis
46
Q

What is changed in the reaction, enzyme or substrate?

A
  • Substrate
47
Q

What happens if substrate shape dosen’t match the active site shape?

A
  • The reaction wont be catalysed and substrate won’t change
48
Q

What is the section of DNA that codes for a particular protein called?

A
  • Gene
49
Q

How does change in temperature affect rate of enzyme-controlled reaction?

A
  • Initially increases rate of enzyme controlled reaction until enzyme denatures, which reduces rate of reaction till 0
50
Q

Initially, why does increse in temperature increase rate of enzyme controlled reaction?

A
  • At higher temp, enzyme and substrate molecules move faster and collide more often
51
Q

What happens to enzymes if temperature becoms too high?

A
  • Amino acid chains start to unravel, changing shape of active site - denaturing enzyme
52
Q

What happens when an enzyme is denatured?

A
  • It loses shape so substrate dosen’t fit in active site anymore
  • So, enzyme can’t catalyse reaction and reaction slows down
  • They can’t return to original shape
53
Q

What are the factors that affect enzyme controlled reactions?

A
  • pH
  • Temperature
  • Enzyme and substrate concentration
54
Q

How does pH affect rate of enzyme controlled reactions?

A
  • If too high or low, it interferes with bonds holding enzyme together, which changes shape of active site and irreversibly dennature enzyme
55
Q

How does enzyme concentration affect rate on enzyme controlled reactions?

A
  • More enzymes present, more likely a substrate will meet up and join with one and join with it, increase in enzyme conc, increase rate of reaction
  • If substrate amount limited, theres a point where enough enzymes to deal with available substrate, so adding more has no further effect
56
Q

How does substrate concentration affect rate of enzyme controlled reactions?

A
  • Higher substrate concentration, faster reaction is more likely it meets up with an enzyme and react
  • Only upto a point, as there are too many substrate molecules for enzymes, all active sites full
57
Q

What are carbihydrate molecules made of/

A
  • monomers that are simple sugars, they join in log chains to make polymers, large complex carbs
58
Q

What and how can carb polymers be broken into?

A
  • Polymer broken down back into suagrs by carbohydrase enzymes
  • Starch broken by amylase
59
Q

What enzye breaks down proteins?

A
  • Protease
60
Q

What monomers make up prtoein?

A
  • Amino acids
61
Q

What are lipids?

A
  • Fats and oils
62
Q

What are lipids synthesised from?

A
  • 3 fatty acid molecules and a gycerol molcule
63
Q

What enzyme breaks down lipids?

A
  • Lipase
64
Q

What do lipase enzymes break lipids down into?

A
  • Fatty acids and glycerol
65
Q

What happenes when food molecules are fully digested?

A
  • They’re absorbed into bloodstream and travel to cells that need them
66
Q

What is respiration?

A
  • Proccess of transferring energy from breakdown of glucose, happens in every cell - a universal chemical process
67
Q

Why is ATP made in respiration?

A
  • Energy transferred by respiration can’t directly be used by cells - its used to make ATP
  • ATP stores energy needed for many cell processes
68
Q

What is respiration controlled by and how does this affect it?

A
  • Controlled by enzymes, so rate of respiration affected by both temperature and pH
69
Q

Cells can respire using glucose as a substrate, what other things can be used as a substrate?

A
  • Organism can break down organic molecules to use as substrate in respiration
70
Q

How is ATP that’s produced in respiration used?

A
  • To synthesis larger molecules form smaller ones to make new cell material
  • For movement, as it can be used tocontract muscle to move
  • To stay warm
71
Q

What do the number of mitochondira in a cell tell you?

A
  • How active the cell is
72
Q

Do muscle cells have a lot of mitochondria and why?

A
  • Yes, becuase they transfer a lot of energy, so they have large quantity of mitochondria
73
Q

Do liver cells have a lot of mitochondria?

A
  • Yes because they carry out many reactions
74
Q

When does anaerobic respiration take place?

A
  • When there isn’t enough oxygen present
75
Q

Why during sternous excersize is there not enough oxygen present?

A
  • Your heart rate cannot increase fast enough tommet the demand of oxygen required
76
Q

How is glucose broken down during anaerobic respiration?

A
  • It is partially broken down and lactic acid is produced
77
Q

How much ATP is produced in anaerobic and aerobic respiration?

A
  • Aerobic - 32ATP

- Anaerobic - 2ATP

78
Q

What is an advantage of anaerobic respiration?

A
  • You can atleast continue to use your muscles
79
Q

What happens after anaerobic respiratoin?

A
  • After you stop excersise you will have an oxygen debt, the extra oxygen required to break down all the lactic acid built up to allow aerobic respiration after
80
Q

Can plants respire anaerobically?

A
  • Under some conditions they can if no O2 present like in waterclogged soils
81
Q

What does anarobic repsiration in plants and fungi make?

A
  • Ethanol and Carbon Dioxide
82
Q

Where does plant get reactants required in photosynthesis from?

A
  • Carbon dioxide diffues from air into plant through stomata

- Water enters from soil through rooh hair cells by osmosis

83
Q

What is some of the gluose made in photoynthesis used for?

A
  • Making larger, complex compounds that plants and alage need to grow
84
Q

Where does photosynthesis in a plant occur?

A
  • In plant’s chloroplasts - they contain cholorphyll which absorbs light
  • Mainly in leaf but a little in lpant stem
85
Q

How is chlorophyll related to photosynthesis?

A
  • Light transfers energy to chlorplats where CO2 and H20 react to make glucose
86
Q

What are 2 stages of photosynthesis?

A
  • Stage 1, Light dependant, energy transferred from light splits water to O2 gas and hydrogen ions
  • Stage 2, Light independant, carbon dioxide combines with hydrogen ions to make glucose
87
Q

What happens to the glucose made in photosynthesis that isn’t used right away?

A
  • Converted into starch - provides a store of energy that can be used at night for respiration
88
Q

What are the factors that affect rate of photosynthesis known as?

A
  • Limiting factors - CO2, temp, light intensity
89
Q

How to calculate rate of photosynthesis?

A

Rate = 1/time

unit - s^-1, min^-1, h^-1

90
Q

How does light intesity affect rate of photosynthesis?

A
  • Light transfers energy needed for photosynthesis
  • As light level increases, photosynthesis rate increases steadily upto certain point
  • At that point, it wont make a difference temp or co2 s limiting factor
91
Q

What is the relationship between distance from lamp and light intensity ?

A
  • They are inversly proprtional and this is known as the Inverse square law
92
Q

What is formula for inverse square law?

A

Light intensity = 1/distance^2

93
Q

How does CO2 affect rate of photosynthesis?

A
  • It is one of reactans for photosyntheis
  • Greater CO2 conc highet rate oh photosynthesis
  • It is also usually the limiting factor
94
Q

How does temperature affect rate of photosynthesis?

A

Photosyntheis is a series of enzyme controlled reactions, higher temp, higher rate of reaction
- Stops at certain point as if temp is too high, enzymes will denature

Ocr Gcse Biology (4 decks)

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