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Biology Edexcel A Alevel > Paper 1: Advance Information > Flashcards

Paper 1: Advance Information Flashcards

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1
Q

Explain what happens in the activation of T helper cells

A
  • Bacterium with antigen on surface is engulfed by macrophage.
  • Macrophage presents antigens on its surface and becomes an APC.
  • The APC eventually find the T helper cell with the complimentary CD4 receptor.
  • Clonal expansion occurs and the T helper cell activates and divides into more T memory cells and T helper cells.
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2
Q

How do hospitals minimise the selection pressure on bacteria?

A
  1. New patients screened on arrival
  2. antibiotics only used when needed and must complete the full course.
  3. Strict hygiene regimens
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3
Q

What do the ribosomes of a prokaryotic cell do and what are they made up of?

A

They are smaller than in eukaryotic cell and make proteins.

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4
Q

Where are ribosomes found?

A

Free in the cytoplasm or attached to the endoplasmic reticulum.

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5
Q

How can biodiversity be compared to different habitats?

A

Using a formula to calculate an index of diversity

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6
Q

What is the primary structure of protiens?

A

The sequence of amino acids in the polypeptide chain.

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7
Q

What is a polypeptide?

A

More than 2 amino acids join together.

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8
Q

How can our knowledge of dendrochronology tell us about past climates?

A

If a ring in a tree was bigger then the conditions for the tree were likely better

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9
Q

What is allopatric speciation?

A

geographic isolation which results in speciation

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10
Q

How are DNA fragments separated?

A

gel electrophoresis

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11
Q

What is clonal expansion

A

T/B cells that are complementary to an antigen undergo rapid mitotic division to form many cloned cells.

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12
Q

latency period

A

when HIV replication drops to a lower level and a person wont experience symptoms.

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13
Q

How is new evidence analysed by the science community?

A

Scientific journals, peer review process and scientific conferences.

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14
Q

What is the role of microorganisms in the decomposition of organic matter and the recycling of carbon?

A

Microorganisms use the corpse as a food source with energy being released through aerobic and anaerobic respiration. Carbon dioxide is released into the atmosphere by the respiring decomposers.

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15
Q

lysis

A

the bursting of a cell

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16
Q

What does ‘translation’ mean in terms of biology?

A

Turning the sequence of bases in the genetic code into a sequence of amino acids.

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17
Q

What happens in the 3 stages of cycle 1 of a PCR?

A
  1. -DNA separates into two strands
  2. -Primers (small pieces of DNA with florescent markers) attach at the start of the STR repeated sequence
  3. -DNA polymerase attach. Nucleotides are added, extending the DNA from the primer. The STR repeated sequence and DNA adjacent is replicated.
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18
Q

What happens in the calvin cycle

A
  • CO2 combines with 5C compound RuBP and is catalysed by Rubisco
  • The 6C compound formed is unstable so breaks down into 2 GP molecules
  • GP is reduced using the hydrogen from reduced NADP and energy stored in ATP into GALP
  • 2/12 GALPs formed create a 6C
  • The remaining 10GALPs are involved in the recreation of RuBP. They rearange to form 6 5C compounds which are then phosphorylated using ATP to form RuBP.
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19
Q

What are the two types of enzymes?

A

Intracellular (catalyse reactions inside cells) or extracellular (produced and secreted by cells that catalyse reactions outside cells)

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20
Q

What is the role of thylakoid space in a chloroplast? and what does it contain?

A

contains enzymes for photolysis

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21
Q

What is the role of a starch grain in a chloroplast?

A

stores the products of photosynthesis

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22
Q

What is an example of a globular protein?

A

Eg. haemoglobin made up of four polypeptide chains. It carries oxygen around the body in the blood. Its soluble so it can be easily transported in the blood. It has haem groups that bind to oxygen.

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23
Q

What does a mononucleotide look like?

A
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24
Q

What are the possible effects of climate change?

A

changing rainfall patterns and changing seasonal cycles

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25
Q

What are the 4 methods proteomics and genomics?

A

DNA Hybridisation, DNA profiling, DNA and protein sequencing and DNA molecular clocks

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26
Q

What assumptions are made when we extrapolate

A

we have enough data to establish the trend accurately and that present trends continue

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27
Q

How does infection of TB occur

A

when droplets containing the bacteria are inhaled into the lungs

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28
Q

what are exons

A

coding regions

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29
Q

What is the cell wall and what is its role?

A

supports the cell made of a glycoprotein

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30
Q

What are eukaryotic cells?

A

They are complex and include all animal and plant cells.

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31
Q

What is thymine replaced with in RNA?

A

Uracil

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32
Q

How does the concentration of the enzymes effect the rate of reaction?

A

The more enzymes there are the more active sites are present and therefore the more likely a substrate molecule is to collide with an active site and form an enzyme substrate complex.

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33
Q

What is the lock and key model?

A

Substrate fits into the enzyme the same way a key fits into a lock.

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34
Q

What are introns

A

non-coding regions

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35
Q

What is the formula to calculate index of diversity?

A

D= N(N-1) / E*n(n-1)

  1. *E = sum of
  2. *N total number of all species
  3. *n total number of one species
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36
Q

How can genetic profiling be used to identify paternity?

A

Offspring inherit one STR from each parent.

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37
Q

What is the structure of A and G?

A

They have a 2 ring structure

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38
Q

What is a monomer?

A

Amino acids

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39
Q

What is the quaternary structure?

A

Some proteins made of several different polypeptide chains held together by bonds. The quaternary structure is the way these polypeptide chains are assembled together.

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40
Q

What are immunoglobulins?

A

antibodies

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41
Q

What are the initial symptoms of TB?

A

Fever, general weakness and severe coughing caused by inflammation of the lungs.

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42
Q

why might these models have limitations

A

Limited data, limited knowledge, changing trends, limitations of computers and failure to include all factors

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43
Q

What is the first sign of decomposition

A

putrefaction when the abdomen turns green

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44
Q

What is the function of the Golgi apparatus?

A

It processes and packages new lipids and proteins. It also makes lysosomes.

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45
Q

What bonds hold together the secondary structure?

A

Hydrogen bonds

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46
Q

How does stomach acid protect the body?

A

kills bacteria ingested

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47
Q

What is speciation?

A

The development of new species.

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48
Q

Habitat

A

Place where an organism lives

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49
Q

What is the sequence of repeated bases in introns know as?

A

short tandem repeats or satellites

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50
Q

What is the role of the stroma in a chloroplast?

A

light independent reaction occurs here

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51
Q

What is primary succession?

A

when there has never been a community before

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52
Q

What is the definition for genotype

A

The alleles a person has eg BB, Bb or bb

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53
Q

What is the rough endoplasmic reticulum

A

A system of membranes enclosing a fluid filled space. The surface is covered with ribosomes.

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54
Q

What is the theory of the evolutionary race?

A

pathogens evolve adaptations that enable them to survive and reproduce.

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55
Q

Describe the structure of an enzyme

A

Enzymes have an active site, which has a specific shape. The active side is the part of the enzyme where the substrate molecules bind to.

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56
Q

What factors effect post mortem cooling

A

Body size, body position, clothing, air movement, humidity and temperature of suroundings.

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57
Q

What are the 4 non specific immune system responses?

A

Lysozyme, inflammation, phagocytosis and antimicrobial proteins

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58
Q

What is the DNA coding strand also known as?

A

The sense strand

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59
Q

What bonds hold together amino acids?

A

Peptide bonds

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60
Q

How does natural selection lead to adaptation and evolution? (6 marker)

A
  1. Mutations can introduce new alleles into a population, so individuals within a population show variation in their phenotypes. Some of these alleles determine characteristics that can make the individual more likely to survive.
  2. Selection pressures such as predation, disease and competition create a struggle for survival.
  3. Individuals without the advantageous allele don’t survive. This means there are fewer individuals and less competition for resources.
  4. Individuals with the advantageous allele are more likely to survive and reproduce and pass on the advantageous allele.
  5. Over time the number of individuals with the advantageous allele increases.
  6. Over generations this leads to evolution as the frequency of the advantageous alleles in the population increases and the favourable adaptation becomes more common.
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61
Q

Why does intense heat slow down decomposition

A

As the enzymes involved in autolysis become denatured.

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62
Q

What are examples of how enzymes catalyse metabolic reactions?

A
  • At a cellular level eg respiration
  • For the organism as a whole eg digestion
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63
Q

What happens in each cycle of a PCR?

A

The process is repeated producing copies that are just the STR sequence fragment.

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64
Q

What is the function of the mitochondrion?

A

The site of the aerobic respiration, where ATP is produced. They’re found in large numbers in cells that are very active and require lots of energy.

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65
Q

What does the smooth ER do?

A

Synthesises and processes lipids.

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66
Q

What is the nature of the genetic code?

A

Triplet code- each adjacent group of 3 bases codes for an amino acid.

Non-overlapping- each triplet code is adjacent.

Degenerate- Several triplets can code for the same amino acid.

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67
Q

How is energy released from ATP in water?

A

The 3rd phosphate ion becomes hydrated forming bonds with the surrounding water molecules. In which lots of energy is released.

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68
Q

What is the structure of ATP

A

adenine, ribose, 3 phosphate groups

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69
Q

What is the function of the ribosome?

A

The site where proteins are made.

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70
Q

What are the two reasons why an enzyme substrate complex lowers the activation energy?

A

If two substrate molecules need to be joined, being attached to the enzyme holds them close together, reducing any repulsion so they can bond more easily.

If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate, so the substrate molecule breaks up more easily.

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71
Q

What is a lysosome?

A

A round organelle surrounded by a membrane, with no clear internal structure.

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72
Q

What is an example of artificial passive immunity?

A

When antibodies are injected into the body

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73
Q

What do bacteria have that viruses do not have?

A

plasma membrane, cytoplasm and ribosomes

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74
Q

What bonds hold together the quaternary structure?

A

Determined by the tertiary structure of the individual polypeptide chains being bonded together. So can be influenced by all mentioned bonds.

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75
Q

When does speciation occur?

A

When populations of the same species become reproductively isolated.

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76
Q

What is an example of natural active immunity?

A

Being exposed to or getting the disease

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77
Q

When can body temperature be useful in determining time of death?

A

during the first 24 hours

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78
Q

What is the role of a granum in a chloroplast?

A

contains a stack of thylakoids

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79
Q

What is used in the light independent reactions

A

carbon dioxide

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80
Q

Mutualism

A

A relationship between two species in which both species benefit

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81
Q

Endemism

A

When a species is unique to a single place and isn’t naturally found anywhere else.

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82
Q

What is the golgi apparatus?

A

A group of fluid filled membrane bound, flattened sacs. Vesicles are often seen at the edges of the sacs.

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83
Q

antigens

A

Foreign material that invades the body

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84
Q

When are 2 species able to share the same habitat

A

Only if they occupy different niches

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85
Q

allele

A

Different version of the a gene which codes for a different version of the same gene

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86
Q

What does the pili of a prokaryotic cell do and what is it made up of?

A

Pili help prokaryotes stick to other cells and can be used in the transfer of genetic material between cells.

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87
Q

What are enzymes?

A

They speed up chemical reaction acting as biological catalysts.

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88
Q

What would happen if a mutation occurs in the gene that codes for the protein that is the enzyme?

A

The primary structure will be different and that could result in the tertiary structure being different.

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89
Q

Why do scientists evaluate new data?

A

To check that the experiments or studies were designed properly and that the conclusions were fair.

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90
Q

How are the fragments of DNA created?

A

Restriction enzymes are used. They will only cut up DNA at specific base sequences. They cut away the STR from the DNA.

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91
Q

What are dipeptides?

A

When 2 amino acids join together.

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92
Q

Why is methane harmful?

A

it absorbs more infrared radiation than a molecule f CO2 does

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93
Q

What are ribosomes composed of?

A

2 subunits: a smaller and larger subunit. The larger subunit contains two tRNA binding sites and the mRNA attaches to the smaller subunit.

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94
Q

What effect does temperature have on decomposition?

A

Warm temps speed it up and lower temperatures slow down decomposition.

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95
Q

How does photosynthesis impact the carbon cycle?

A

The reduction of CO2 into organic substance and the release of oxygen as a waste product

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96
Q

How does inflammation occur?

A

The damaged white blood cells release special chemicals eg histamine. Causing the arterioles in the area to dilate and increasing the permeability of the capillaries. Plasma fluid, white blood cells and antibodies leak from the blood into the tissue causing oedema.

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97
Q

WHat is evolution

A

change in allele frequency over time

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98
Q

What are fibrous proteins? and what are their features?

A

Long, insoluble polypeptide chains that are tightly coiled round each other to form a rope shape.

The chains are held together by lots of bonds which makes the proteins strong.

Because they’re strong they can be found in supportive tissue.

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99
Q

Name 5 abiotic factors that effect the numbers and distribution of organisms

A

Solar energy input, climate, oxygen concentration, pollution catastrophe.

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100
Q

what might cause the climax community to change

A

unless the conditions in the habitat changes the climax community is stable

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101
Q

What is net primary productivity?

A

gross primary productivity - respiration

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102
Q

How can biodiversity be measured within a habitat?

A

Using species richness

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103
Q

What does the cell wall of a prokaryotic cell do and what is it made up of?

A

Supports the cell and prevents it from changing shape. Its made of a polymer called murein. Murein is a glycoprotein (a protein with a carbohydrate attached)

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104
Q

What 5 biotic factors effect the numbers and distribution of organisms

A

competition for resources, grazing, predation, disease and parasitism mutualism

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105
Q

Heterozygote

A

Bb

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106
Q

What is the secondary structure of proteins?

A

The polypeptide chain doesn’t remain flat and straight. Hydrogen bonds form between the amino acids in the chain. This makes it automatically coil into an alpha helix or a beta pleated sheet.

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107
Q

What are the 8 categories in the classification hierarchy?

A
  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
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108
Q

Why is the arrangement of the DNA double helix the way it is?

A

The hydrophilic phosphate groups are on the outside of the molecule and the hydrophobic bases lie within the molecule.

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109
Q

How does a protein’s primary structure determine its 3D structure and properties?

A

The amino acid sequence of a protein determines what bonds will form and how the protein will fold up into its 3D structure.

The 3D structure of a protein relates to its properties. Its properties relate to its function in the body.

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110
Q

why does the body turn greenish after death?

A

The formation of sulfhaemoglobin in the blood

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4
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111
Q

Give examples of physiological adaptations

A

Brown bears hibernate- they lower their rate of metabolism over winter. This conserves energy, so they don’t have to look for food in the months when its scarce.

Some bacteria produce antibiotics- these kill other species of bacteria in the area so that means there’s less competition.

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112
Q

How does the skin protect the body?

A

tough physical barrier consisting of keratin

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113
Q

What happens once the temperature becomes too high?

A

The shape of its active site is lost and the enzyme substrate complex no longer forms as it is denatured.

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114
Q

What is a ribosome?

A
  • A very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum.
  • Its made up of proteins and RNA.
  • Its not surrounded by a membrane.
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115
Q

Where are B cells produced?

A

bone marrow

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116
Q

What are physiological adaptations?

A

Processes inside an organisms body that increase the chance of survival.

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117
Q

Understand how the … of multicellular organisms are organised into …., and …… into …… and …….. into ……..

A

Cells tissues tissues organs organs systems

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118
Q

What bonds hold together the primary structure?

A

Peptide bonds

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119
Q

What is a prokaryotic cell made up of?

A
  1. Cell wall
  2. Capsule
  3. Plasmid
  4. Flagellum
  5. Pili
  6. Ribosomes
  7. Mesosomes
  8. Circular DNA
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120
Q

What is it called when ADP and phosphate join together?

A

Phosphorylation

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121
Q

Autolysis

A

When the body’s own enzymes, from the digestive tract and from lysosomes, break down cells.

122
Q

When does HIV become AIDS?

A

when the CD4 (T helper cell) count goes below 200

123
Q

How can one gene give rise to more than one protein?

A
  1. Through post transcriptional changes to mRNA.
  2. The introns are removed leaving only the exons. This is mRNA.
  3. Before this it is called pre-mRNA when introns were still present.
  4. Once the introns are removed the exons can be spliced in many different ways leading to more than one protein.
124
Q

What does the equation p2 + 2pq + q2 = 1 stand for?

A

p2 = the frequency of the homozygous dominant genotype

2pq = the frequency of the heterozygous genotype

q2 = the frequency of the homozygous recessive genotype.

125
Q

What is the impact of a mutation?

A

The order of DNA bases in a gene determines the order of amino acids in a particular protein. If a mutation in a gene, the primary structure (the sequence of amino acids) could be altered. Which could change the final 3D shape of the protein so it doesn’t work properly.

126
Q

What is the role of the inner membrane in a chloroplast?

A

Regulate the passage of substances

127
Q

What do mesosomes of a prokaryotic cell do and what are they made up of?

A

Mesosomes are inward folds in the plasma membrane. They are believed to be involved in cellular processes.

128
Q

What are globular proteins? and what are their features?

A

They are round and compact proteins made up of multiple polypeptide chains.

The chains are coiled up so that hydrophilic parts of the chain are on the outside of the molecule and hydrophobic are on the inside..

This makes the proteins soluble so they’re easily transported in fluids.

129
Q

What is proteomics

A

Study of proteins

130
Q

What are mesosomes?

A

folds in the cell membrane

131
Q

What does a lysosome do?

A

Contains digestive enzymes. These are kept separate from the cytoplasm by the surrounding membrane and can be used to digest invading cells or to breakdown worn out components of the cell.

132
Q

What are prokaryotic cells

A

They are smaller and simpler eg bacteria

133
Q

Why is it though that increased CO2 levels cause global warming?

A

There is a strong correlation between temperature and carbon dioxide concentration

134
Q

Describe the process of DNA replication

A
  1. Enzyme DNA helicase breaks the hydrogen bonds between bases on the two polynucleotide strands. This makes the helix unwind to form two single strands.
  2. Each original single strand acts as a template for a new strand. Complementary base pairing means that free floating DNA nucleotides are attracted to their complementary exposed bases on each original template strand.
  3. Condensation reaction join the nucleotides of the new strands together- catalysed by the enzyme DNA polymerase. Hydrogen bonds form between the bases on the original and new strands.
  4. Each new DNA molecule contains one strand from the original DNA molecule and one new strand.
135
Q

What 2 factors can we do to help maintain the balance?

A

Sustainable resources including biofuels and reforestation

136
Q

What are the two main types of lymphocytes?

A

T cells and B cells

137
Q

What temperature do the 3 stages of a PCR occur at?

A

95C, 55C and 70C

138
Q

What are bacteriostatic antibiotics?

A

Bacteriostatic antibiotics inhibit the growth of bacteria through stopping protein synthesis and production of nucleic acids so bacteria cant divide and grow.

139
Q

What are flagellum and what is their role?

A

Long hair like structure that rotates To make bacterium move.

140
Q

What bonds hold the peptide chains of a T cell?

A

Disulphide bonds

141
Q

Species diversity

A

The number of different species and the abundance of each species in an area.

142
Q

How do introns help scientists create a unique DNA profile?

A

they are unlikely to have the same combination of STRs with the same number of repeats within.

143
Q

How does HIV replicate?

A
  1. HIV surface protein binds to cell receptors. The virus envelope fuses with cell surface membrane.
  2. The virus uses the enzyme reverse transcriptase to turn the HIVs RNA into DNA.
  3. Integrase inserts virus DNA into host DNA.
  4. The cells natural process of protein synthesis and host cell enzymes are used to make viral proteins from the viral DNA found within the human DNA.
  5. The viral proteins are assembled into new viruses which bud from the cell and go to infect other cells.
144
Q

What are the 2 sub-definitions of biodiversity?

A

Species diversity

Genetic diversity

145
Q

What are the products of the light independent reaction used for?

A
  1. They are used by plants and animals in respiration
  2. Synthesis of new biological molecules eg polysaccharides, amino acids, lipids and nucleic acids.
146
Q

What is the function of the nucleus

A

Controls the cells activities (by controlling the transcription of DNA) DNA contains instructions to make proteins. The pores allow substances to move between the nucleus and the cytoplasm.

147
Q

Why do different characteristics become more common of different sides of the physical barrier?

A

Conditions on either side of the barrier will be different as there might be a different climate on each sides.

148
Q

What does the capsule of a prokaryotic cell do and what is it made up of?

A

Made up of secreted slime it helps to protect the bacteria from attack by cells of the immune system.

149
Q

What are bactericidal antibiotics

A

They kill bacteria by destroying their cell wall and thus causing them to burst (lysis)

150
Q

What is the mitochondrion?

A

They’re usually oval-shaped. They have a double membrane- the inner one is folded to form structures called cristae. Inside the matrix, which contains enzymes involved in respiration.

151
Q

Explain the stages of the light dependant reaction

A

NAME?

152
Q

What is an example of a fibrous protein?

A

e.g. Collagen which is a strong fibrous protein that forms connective tissue in animals.

153
Q

How does biomass impact the carbon cycle?

A

Plant material accounts for the majority of photosynthesis in the world

154
Q

Succession

A

Process by which an ecosystem changes over time. The biotic conditions change as the abiotic conditions change.

155
Q

What happens if two species try to occupy the same niche?

A

They will compete with each other. One species will be more successful than the other until only one species is left.

156
Q

What is deflected succession?

A

when human activity causes a community to remain stable because it prevents succession from running its course

157
Q

How might climate change impact the development and life cycle of animals

A

If environmental cues trigger their behaviour or development. Spawning and hatching and growth rates are most likely to be effected.

158
Q

Population

A

members of the same species that occupy the same area

159
Q

Where does the light dependent reaction take place?

A

Thylakoid membranes

160
Q

What are the first organism to colonise bore surfaces

A

lichen

161
Q

What impact of the effects of climate change might it have on plants and animals

A

distribution of species, altered development and life cycles

162
Q

How do you calculate biodiversity using the heterozygosity index?

A

Number of heterozygotes / number of individuals in the population

163
Q

Genetic diversity

A

The variation of alleles within a species (or a population of a species)

164
Q

What bond holds together adjoining nucleotides via the sugar (ribose or deoxyribose) and the phosphate?

A

phosphodiester bonds

165
Q

How many hydrogen bonds does A and T have?

A

2 hydrogen bonds

166
Q

What is the centriole?

A

Small, hollow cylinders made of microtubules (tiny protein cylinders) Found in animals, but only some plant.

167
Q

How many hydrogen bonds do C and G have?

A

3 hydrogen bonds

168
Q

Where is DNA in bacteria?

A

free floating in the cytoplasm

169
Q

How does gut and skin flora protect the body?

A

natural bacterial flora competes with pathogens for food and space.

170
Q

Why is an enzymes primary structure so important?

A

As the enzymes tertiary structure is determined by the primary structure. And the tertiary structure determines the enzymes active site which determines if the complementary substrate will fit into the active site.

171
Q

What is the sequence of events during rigor mortis?

A

1 Muscles become starved of oxygen and oxygen dependant reactions stop 2 Respiration of the cells becomes anaerobic and produces lactic acid 3 pH of cell falls, inhibiting enzymes and thus inhibiting anaerobic respiration 4 ATP needed for muscle contraction is no longer produced so bonds between muscles become fixed 5 proteins can no longer move over one another so the muscles and joins become fixed.

172
Q

How is a DNA profile made?

A

-A sample of DNA is obtained -Fragments of different lengths are created through cutting up the DNA -The fragments are separated and visualised -Then the profile is compared to another

173
Q

phagocytosis

A

when phagocytes engulf and destroy antigens.

174
Q

Why are enzymes highly specific?

A

Due to their tertiary structure

175
Q

What is the definition for phenotype

A

The characteristics displayed by an organism eg brown eyes

176
Q

What is the basic structure of an amino acid? and draw one

A
177
Q

What types of errors can occur during DNA replication?

A
  1. Substitution
  2. Deletion
  3. Insertion
  4. Duplication
  5. Inversion
178
Q

what is a dominant species of a community?

A

the one that exerts an overriding influence over the rest of the plants etc. sometimes there is more than one and they are often the most abundant species.

179
Q

which is the most potent greenhouse gas

A

methane

180
Q

What is sympatric speciation?

A

a species evolves into a new species without a physical barrier

181
Q

What has happened to biodiversity over time?

A

Over time the variety of life has become extensive but it is now being threatened by human activity.

182
Q

what is often a feature of pioneer species?

A

seeds widely dispersed by wind, rapid growth, short life cycle and abundant seed production.

183
Q

Explain the process in which proteins are transported in cells?

A
  1. Proteins are made at the ribosomes on the rough ER.
  2. New proteins produced at the rough ER are folded and processed in the rough ER.
  3. The proteins are then transported from the ER to the Golgi apparatus in vesicles.
  4. At the Golgi apparatus, the proteins may undergo further processing (further modification)
    1. The proteins enter more vesicles to be transported around the cell.
184
Q

What are the 2 factors likely responsible for the carbon cycle not being in balance?

A

combustion of fossil fuels and deforestation

185
Q

what curve does the falling of body temperature follow?

A

Sigmoid curve

186
Q

What is the basic structure of mononucleotides?

A

Deoxyribose or ribose linked to a phosphate and a base, including thymine, uracil, cytosine, adenine or guanine.

187
Q

What happens if 2 species live in the same habitat and have exactly the same ecological niche

A

They will compete until the better adapted of the two outcompetes the other and excludes it from the habitat.

188
Q

What is the role of the outer membrane in a chloroplast?

A

permeable to CO2 and H2O

189
Q

How do you calculate net primary productivity

A

NPP = GPP - Plant Respiration

190
Q

Give examples of anatomical adaptations

A

Otters have a streamlined shape making it easier to glide through the water. This makes it easier for them to catch prey and escape predators, increasing their chance of survival.

Whales have thick layer of blubber which helps keep them warm in the cold sea. This increases their chance of survival in places where their food is found.

191
Q

What bonds hold together the tertiary structure?

A
  1. Ionic- attractions between +ve and -ve charges.
  2. Disulfide bonds- When two molecules of the amino acid cystine come close together, the sulfur atom in one cystine bonds to the other sulfur.
  3. Hydrophilic and hydrophobic interactions
  4. Hydrogen bonds
192
Q

What is an example of natural passive immunity?

A

the crossing of mother’s antibodies through the placenta and/or breast milk

193
Q

What are plasmids and what is their role?

A

Small loops of DNA that aren’t part of the chromosome.

194
Q

What are mutations?

A

Changes to the base sequence of DNA

195
Q

How is DNA obtained?

A

-Tissue sample is broken down in a buffer solution -The small suspended particles inc DNA are separated from the rest of the cell debris -Protease enzymes are incubated with the suspension to remove proteins -cold ethanol is added to precipitate out the DNA -The DNA is then washed in a buffer solution multiple times

196
Q

What is a species?

A

A group of similar organisms that can reproduce to give fertile offspring.

197
Q

What is the tertiary structure of proteins?

A

Coiled or folded chain of amino acids are coiled or folded further. More bonds form between different parts of the polypeptide chain, including hydrogen bonds and ionic bonds. Disulphide bonds can also form.

Proteins made of a single polypeptide chain, the tertiary structure forms their final 3D structure.

198
Q

How do lysozymes protect against pathogens?

A

found in tears they kill bacteria by breaking down their cell walls. Also found in saliva and nasal secretion.

199
Q

What happens once TB is in the lungs?

A

Bacteria is taken up by a phagocyte. Bacteria survive and replicate inside phagocytes. The infected phagocytes are sealed off in the lungs in tubercles. When in tubercles the bacteria is dormant and shows no obvious symptoms. The dormant bacteria might later become active and overcome the immune system. Reactivation is more likely in people with a weakened immune system.

200
Q

What does the rough ER do?

A

Folds and processes proteins that have been made at the ribosomes.

201
Q

What are the two ways TB kills a person?

A

In the lungs- respiratory failure If it spreads- organ failure

202
Q

What does the flagellum of a prokaryotic cell do and what is it made up of?

A

Long hair like structure that rotates to make the prokaryotic cell move. Not all prokaryotes have a flagellum. Some have more than one.

203
Q

What does the Hardy Weinberg equation predict? and under what conditions?

A

That the frequency of alleles in a population wont change from one generation to the next.

But it has to be a large population where there is no immigration, emigration ,mutations or natural selection. There also needs to be random mating.

204
Q

How long does methane stay in the atmosphere?

A

it only stays in the atmosphere for 12 years before it reacts with oxygen to form CO2 and water

205
Q

What are behavioural adaptations?

A

Ways an organisms acts that increase its chance of survival.

206
Q

How else might a population become reproductively isolated?

A

Geographical isolation or random mutations that introduce new alleles into the population.

207
Q

What are anatomical adaptations?

A

Structural features that increase an organisms chance of survival.

208
Q

What is the classification of organisms based off of?

A

Their phenotypes, genotypes and how related they are.

209
Q

What does the plasmid of a prokaryotic cell do and what is it made up of?

A

Plasmids are small loops of DNA and contain genes for things like anti-biotic resistance. They are not always present and some bacteria contain several.

210
Q

What is the definition for gene?

A

A sequence of bases on a DNA molecule that codes for a protein, which results in a characteristic.

211
Q

What is an organisms niche?

A

An organism’s interactions with other living organisms and its interaction with the non living environment.

212
Q

Why do reactions occur in enzymes slowly at low temperatures?

A

Enzymes and substrate have low kinetic energy so move slowly and do not collide often

213
Q

What is the definition for recessive

A

An allele whose characteristic only appears in the phenotype if two copies are present.

214
Q

How do enzymes speed up the rate of reaction

A

They lower the activation energy.

215
Q

why do peat bogs highlight a changing climate?

A

peat is the accumulation of partially decayed organic matter. Pollen can be used to reconstruct the past climates.

216
Q

How might climate change impact the distribution of species?

A

Some species may benefit from the change in climate and become dominant while others may be lost due to competition.

217
Q

Ecosystem

A

the interaction between living organisms and the environment in a given area.

218
Q

What is the impact on plants if enzymes denature

A

Higher temp and lower soil moisture as the enzymes denature

219
Q

What is CF caused by? and what happens as a result?

A
  • A mutation in the gene that codes for the CFTR protein.
  • CFTR is a channel protein. It transports chloride ions out of the cell and into the mucus- this causes water to move into the mucus by osmosis, which makes mucus watery.
  • Mutant CFTR protein is much less efficient at transporting chloride ions our of the cell so less water moves out by osmosis. This makes the mucus of people with CF abnormally thick and sticky.
  • The thick and sticky mucus causes problems in the respiratory, digestive and reproductive systems.
220
Q

How are global trends predicted?

A

Extrapolation- extending the line

221
Q

How might climate change impact the development of plants?

A

For plants photosynthesis may initially be faster but eventually enzymes will no longer be at optimum and start to denature.

222
Q

What does the circular DNA of a prokaryotic cell do and what is it made up of?

A

They are one long coiled up strand and are not attached to any histone proteins.

223
Q

What does the equation p + q = 1 stand for?

A

p = the frequency of the dominant allele

q = the frequency of the recessive allele

224
Q

Describe the process of translation of DNA

A
  1. mRNA attaches to a ribosome and tRNA molecules carry amino acids to the ribosome.
  2. A tRNA molecule with an anticodon that’s complementary to the start codon on the mRNA attaches itself to the mRNA by complementary base pairing.
  3. A second tRNA molecule attaches itself to the next codon on the mRNA in the same way.
  4. The two amino acids attached to the tRNA molecule are then joined together by a peptide bond. The first tRNA molecule moves away, leaving its amino acid behind.
  5. The ribosome moves along to the next codon.
  6. A third tRNA molecule binds to that codon on the mRNA. Its amino acid binds to the first two and the second tRNA molecule moves away.
  7. This process continues, producing a chain of linked amino acids (a polypeptide chain) until there’s a stop codon on the mRNA molecule.
  8. The polypeptide chain moves away from the ribosome and translation is complete.
225
Q

What is the role of thylakoid membranes in a chloroplast?

A

contains chlorophyll and electron carriers and is involved in light dependant reactions

226
Q

How does using sustainable resources help manage the conflict between human needs and conservation?

A

They are renewable and carbon dioxide neutral

227
Q

Where are T cells produced?

A

thymus

228
Q

How do you produce a DNA profile?

A

-Double stranded DNA + restriction enzymes and the DNA is cut into fragments - Fragments of double stranded DNA are loaded into the wells of agarose gel in a tank -Negatively charged DNA moves towards the positive electrode and the fragments separate into invisible bands. -DNA transferred to a nylon membrane. -Membrane placed in bag with DNA probe . -Probe binds to fragments with a complimentary sequence -If DNA probe is radio active x-ray is used. If florescent, it is viewed using UV light.

229
Q

What are the 3 ways the body is protected from infection?

A

Skin, stomach acid, and gut and skin flora.

230
Q

What are the three domains?

A

Bacteria, Archaea and Eukaryota

231
Q

genome

A

all the DNA in a cell (all the genes)

232
Q

What is the definition for dominant

A

An alleles who’s characteristic appears in the phenotype even when there’s only one copy.

233
Q

What alters the tertiary structure of an enzyme?

A

pH or temperature

234
Q

How do antimicrobial proteins provide a defence against pathogens?

A

They diffuse into the surrounding cells where it prevents microbes from multiplying. It inhibits microbial protein synthesis.

235
Q

How does reforestation help manage the conflict between human needs and conservation?

A

Newly planted trees are rapidly growing and photosynthesising with little respiration so they are net absorbers.

236
Q

What is it called when ADP and phosphate break apart?

A

Hydrolysis

237
Q

What happens in colonisation

A

pioneer species colonise as they are the only organisms that can cope with extreme temperatures, lack of soil, water and nutrients.

238
Q

What is the equation for photosynthesis?

A

6CO2 + 6H2O ——> C6H12O6 + 6O2

239
Q

Homozygote

A

BB or bb

240
Q

What can influence conclusions about controversial issues?

A

They can be impacted by who is reaching those conclusions

241
Q

Biodiversity

A

The variety of living organisms in an area

242
Q

Why is pollen useful

A

each plant has a distinctive type of pollen and pollen has a tough outer layer and are produced in vast amounts

243
Q

What causes changes in allele frequencies?

A

Mutations will take place independently and different characteristics will be advantageous, so the allele frequencies will lead to changes in each population.

244
Q

What is gross primary productivity?

A

The rate at which energy is incorporated into organic molecules by an ecosystem

245
Q

What do pioneer species do?

A

they start to break up the rock surface which allows organic matter to accumulate, allowing a new species to join

246
Q

What is the template strand also known as?

A

The antisense strand

247
Q

What reaction holds together polypeptides and when is this reversed?

A

Condensation reaction forms the bonds holding the amino acids together and the bonds are hydrolysed during digestion.

248
Q

What is it called where the rate of reaction is highest?

A

Optimum temperature

249
Q

Describe the process of transcription?

A
  1. DNA unwinds and H bonds are broken
  2. Coding strand used for mRNA synthesis
  3. RNA polymerase used to join RNA nucleotides
  4. Complementary base pairing A with U not T
250
Q

What kills a person with AIDs?

A

Opportunistic infections

251
Q

What can enzymes affect?

A

Structures in an organism eg production of collagen and functions eg respiration

252
Q

What is the definition for an allele

A

A different version version of a gene

253
Q

What is the structure of C and T

A

They have 1 ring

254
Q

What is evolution?

A

The change in allele frequency

255
Q

What is a gene?

A

A sequence of bases on a DNA molecule that code for a sequence of amino acids on a polypeptide chain.

256
Q

Explain the role of T killer cells

A

A bacterium infects cell of host. The cell presents the antigen and becomes an APC. T killer cell with a complimentary receptor binds to the APC. Cytokines stimulate the differentiation of the T killer cell into T killer memory cells and active T killer cells. The clones of the active T killer cells bind to infected cells presenting antigens. T killer cell release chemicals that cause pores to form in the infected cell, causing lysis. The infected cell dies.

257
Q

What are enzymes?

A

Proteins

258
Q

What is the role of dna loop in a chloroplast?

A

contains genes for some of their proteins

259
Q

What is genomics

A

the study of genomes (DNA)

260
Q

what is the overall aim of photosynthesis

A

to split apart the strong bonds in water molecules, storing the hydrogen in a fuel (glucose) by combining it with carbon dioxide and releasing oxygen into the atmosphere.

261
Q

What are examples of how a physical barrier may cause geographical isolation?

A

Floods, volcanic activity, eruptions and earthquakes.

262
Q

What is CF?

A

It is caused by a recessive allele so they must inherit one recessive allele from each parent. If one person is heterozygous they wont have it but they’ll be a carrier.

263
Q

How can biodiversity be measured within a species?

A

Using genetic diversity

264
Q

How did Meselson and Stahl’s classic experiment support the theory of semi-conservative DNA replication?

A
  1. Two samples of bacteria were grown- one in a nutrient broth containing light nitrogen and one with heavy nitrogen. As bacteria reproduced they took up nitrogen to make the nucleotides so gradually nitrogen became a part of the DNA.
  2. They placed bacteria from the heavy broth in the light nitrogen broth and allowed one round of DNA replication.
  3. They then centrifuged it and found that the newly replicated DNA sat in the middle, suggesting its semi-conservative.
265
Q

What are ribosomes and what is their role?

A

produce proteins from mRNA

266
Q

What is the function of the nucleolus?

A

The nucleolus makes ribosomes

267
Q

What bonds holds the bases of the polynucleotides together?

A

Hydrogen bonds

268
Q

What are proteins made up of?

A

One or more polypeptides.

269
Q

Community

A

the interaction of different species in the same area

270
Q

What is the same and what is different about STR on different chromosomes

A

They occur at the same place (same loci) however the number of times they are repeated varies

271
Q

How does evolution occur

A

Through gene mutation and natural selection

272
Q

What is the smooth ER?

A

A system of membranes enclosing a fluid filled space but has no ribosomes.

273
Q

Why is it important for the scientific community to critically evaluate new data?

A

So scientists can share their discoveries in meetings and scientific journals. If scientists generally agree it can lead to an organism being reclassified or lead to changes in the classification system structure.

274
Q

How is energy stored in ATP

A

ADP + Phosphate ion join together forming ATP in water. To make ATP the phosphate ion must be separated from the water molecule which requires energy.

275
Q

What changes can cause reproductive isolation?

A
  1. Seasonal changes- individuals from the same population develop different flowering or mating seasons, or become sexually active at different times of the year.
  2. Mechanical changes- changes in genitalia prevent successful mating.
  3. Behavioural changes- A group of individuals develop courtship rituals that aren’t attractive to the main population.
276
Q

How does death and decay impact the carbon cycle?

A

CO2 is released during the breakdown by microbes

277
Q

What is the function of centrioles?

A

Involved with the separation of chromosomes during cell division.

278
Q

What is an example of artificial active immunity?

A

when vaccinations stimulate the immune system leading to production of antibodies

279
Q

What is the structure of a strand of DNA and RNA?

A

polynucleotides composed of mononucleotides linked through condensation reactions.

280
Q

How does respiration impact the carbon cycle?

A

The oxidation of organic substance into simpler inorganic compounds such as COs and water

281
Q

Explain what happens once the antibodies are produced by the B cell

A

Antibodies bind to the bacteria with antigens on the surface and label them. Antibodies bind to the antibody receptors on a macrophage. The macrophage engulfs the antibodies and bacterium. Lysosomes fuse with the vacuole releasing the digestive enzymes that destroy the bacterium.

282
Q

What is the description of the nucleus?

A

A large organelle surrounded by a nuclear envelope which contains many pores. The nucleus contains chromatin (made from DNA and proteins) and the nucleolus.

283
Q

How do you investigate the effects of antibiotics on bacterial growth?

A

-Sterile pipette to transfer bacteria to agar plate -Use sterile forceps to place paper discs soaked with different antibiotics. -Lightly tape lid, invert and incubate at 25C for 24-48 hrs -The larger the clear zone the more the bacteria were inhibited from growing.

284
Q

when can forensic entomology not be used?

A

If temperature conditions of the body haven’t been fairly constant

285
Q

What are the two nucleotide strands described as being?

A

Antiparallel as they run in opposite directions

286
Q

Phagocytes

A

white blood cells that engulf antigens. Inc neutrophils and macrophages.

287
Q

What is a capsule and what is its role?

A

protects the bacterium from attack by cells of the immune system

288
Q

What is crucial to speciation?

A

Reproductive isolation (some kind of isolating mechanism) that prevents successful interbreeding and prevents gene flow

289
Q

Give examples of an organisms behavioural adaptations

A

Possums sometimes play dead, they play dead to escape attack which increases their chance of survival.

Scorpions dance before mating

290
Q

What is the definition for incomplete dominance?

A

When a trait for a dominant allele isn’t completely shown over the trait produced by the recessive allele, so both alleles influence the phenotype.

291
Q

What would happen if the substrate concentration became the limiting factor?

A

The addition of more enzyme molecules would make no effect on the rate of reaction.

292
Q

What are the complementary base pairs in DNA?

A

A and T, and C and G

293
Q

What is the induced fit model?

A

The enzyme substrate complex do have to fit together in the first place but the enzyme substrate complex changed shape slightly to fit. This locks the substrate even more tightly to the enzyme.

294
Q

What are the two Hardy Weinberg equations?

A

p + q = 1

p2 + 2pq + q2 = 1

295
Q

What are pili and what is their role?

A

Short hair like structures Pili help bacteria stick together and to other cells

296
Q

How do the rough ER and Golgi apparatus help in the formation of extracellular enzymes?

A

The extracellular enzymes are modified in the vesicles and then are transported around the cell and then moved to the cell and secreted.

297
Q

What are 4 ways we can recognise that climate change is real?

A

CO2 levels, temperature records, pollen in peat bogs and dendrochronology

298
Q

What kind of proteins are made at the rough ER? vs in free floating ribosomes in the cytoplasm?

A

Rough ER- Proteins that are excreted or attached to the cell membrane

Free ribosomes- make proteins that stay in the cytoplasm

299
Q

What is molecular phylogeny and what does it look at?

A

Looks at molecules (DNA and proteins) to see how closely related organisms are.

300
Q

what is secondary succession?

A

on bare soil where an existing community has been cleared eg ploughed field or a forest fire

Biology Edexcel A Alevel (15 decks)

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