Biology Random Retrieval Y13

What enzyme is needed in a PCR reaction ?

What causes epigenetic markers to be added or removed from DNA?

Which of the following would NOT increase your exposure to oestrogen?

Name the method by which DNA replicates.

A student is using a quadrat to estimate percentage cover of clover on the school field. What is the most accurate way to do this?

Natural Selection means that over time the frequency of beneficial alleles in a population will do what?

Why are women far less likely to show sex linked disorders?

What is the definition of 'homozygous'?

Which of the following are features of slow twitch muscle fibres:

A)Lots of aerobic respiration
B)Lots of mitochondria
C)Low levels of myoglobin

The image above shows a muscle fibre. What is the function of organelle E?

The cone density is highest on the fovea in the centre of the retina. In a human fovea there are 150 000 cones per mm2. The diameter of a human fovea is 1.2 mm. Calculate the number of cones on the human fovea.

What type of sodium channels are opened when a Pacinian corpuscle is stimulated?

True or False: Synapses can only transmit an impulse in one direction?

On the diagram, F is a voltage gated ion channel on an excitatory synapse, but which type of ion does it allow through?

When an action potential is generated, there is a temporary reversal of the polarity of the neurone membrane at that point. Does this mean that:

The above diagram shows the Phosphorus cycle. Name type of organism which carries out process A?

Which process can occur due to the actions of Nitrosomonas bacteria?

Which part of the mitochondria is represented by A?

What is represented by molecule D?

Name the enzyme that converts A to B.

True or False : Fungi can increase the surface area of roots

Which process can occur due to the actions of Nitrobacter bacteria?

Which term describes an organism which feeds on dead organic matter and digests their food externally? (watch your spelling)

Suggest the most appropriate units for primary productivity.

The student found that the coloured liquid moved 1.5 cm in 24 hours. The diameter of the lumen (hole) of the capillary tubing was 1 mm.The volume of a capillary tubing is given by πr²l, where π is 3.14 and l = length. Calculate the volume of gas produced in cm³ hour^-1.

The diagram represents anaerobic respiration, name substance 'W'.

As the ETC flows, what will happen to the pH of A?

What is the final electron acceptor of the ETC?

Molecule Z represents ATP. How is this molecule of ATP generated?

How many molecules of Y will be produced by the krebs cycle from a single molecule of glucose?

Which two processes turn Citrate into the 5C intermediate?

What happens to molecule C?

How many times does the Krebs cycle happen per glucose molecule?

Where does the Krebs Cycle occur?

If 'X' on graph A represents 'Light Intensity', what effect would increasing carbon dioxide have on the line (represented in green on the diagram)?

Which graph represents the effect of changing the temperature on the rate of photosynthesis?

Name substance D

Name substance A

Which chemical does 'F' represent?

The splitting of water at PSII creates molecules A & B, what do A and B represent?

What is the role of phosphocreatine in muscle contraction?

The muscle filament in the above diagram is relaxed, what would happen to the following zones when it contracts?

When light falls on cells 1 and 2, only one spot of light is seen. But, when light falls on cells 2 and 3, two spots of light are seen. Say why?

Point C is the point where most colour sensitive photoreceptor cells are located. What is it called?

Name part A on the above diagram.

What term is used to describe when more than one presynaptic neurone releases its neurotransmitter onto single post-synaptic neurone? ( Type your answer carefully)

Whether a synapse is excitatory or inhibitory depends on what?

On the diagram, F is a voltage gated ion channel on an excitatory synapse, but which type of ion does it allow through?

Why does an increase in temperature ( up to 40 degrees) cause an increase in the speed of conduction along a neurone?

Name the term given to the 'jumping' of an action potential long a myelinated neurone.( Type in your answer)

Once an action potential has been generated, what causes the next section of the axon membrane to become depolarised?

True or False: A stronger stimulus will generate more frequent action potentials.

True or false: If more sodium channels are opened by a stimulus, then the action potential which is generated is bigger.

The period of time after an action potential, when another action potential cannot pass along that section of a neurone is called the ____________ period ( Watch your spelling).

Put the above events ( A-F) in order for the passage an action potential.

Which word best describes the charge distribution across a resting axon plasma membrane?

When an neurone axon is at rest, what charge is the extra cellular fluid compared to the cytoplasm?

• a) Simple Diffusion
• b) Facilitated Diffusion
• c) Active Transport

Blow fly maggots have a light sensitive spot on their head, which they use to move away from light. Is this taxis or kinesis?

What does Darwin's experiment where he removed a shoot tip then replaced it show?

What word describes the growth response of a plant to a stimulus?

What is the native climax community in the UK?

Between stages B and C, what will happen to soil depth?

What term do we use to describe lichen and mosses in succession?

What is the equation for Mark Release Recapture?

You can also use a transect to sample a population. When should a transect be used?

A mild winter and a warm spring meant that the population of robins (birds which feed on insects) increased. This was due to the above average biomass of insects, so more young robins survived. However the following winter was very cold so fewer insects were available in the spring, and the robin population decreased. Is the decrease in robin population, intraspecific competition or interspecific competition?

What type of speciation is caused by reproductive Isolation, but without a physical barrier between two populations?

What type of variation is show in the graph?

Natural Selection is when organisms which are better adapted are more likely to survive and pass on their genes. Factors which affect the chance of survival are called selection pressures. These can be positive ( advantageous) or negative ( disadvantageous). Which of these is a negative selection pressure?

Natural Selection is when organisms which are better adapted are more likely to survive and pass on their genes. Factors which affect the chance of survival are called selection pressures. These can be positive ( advantageous) or negative ( disadvantageous). Which of these is a negative selection pressure?

The probability of an individual having Cystic Fibrosis is about 1 in 2500 in the UK. How many individuals will suffer with Cystic Fibrosis in a city of 1.2 million people in it's population?

Drosophila is a type of fruit fly which is used in many genetic experiments. It has two alleles for eye colour : Red ( R) and White (r). If 0.8 of the alleles are red, how many are white?

What represents the total allele frequency in a population?

The Hardy Weinberg principle only applies to a population that is or has ____.

The actual ratio of phenotypes after several matings between the above two hamsters was more similar to 6:1:1:6. How are the alleles linked?

What is an autosome?

What is the best definition of a 'dominant allele'?

What is the definition of 'homozygous'?

What is a gene?

If you start with a single copy of template DNA, how many copies would you have after 10 cycles?

Sometimes, two marker genes are used: The first marker gene is often an antibiotic resistance gene to show if the plasmid is present; the bacteria can only grow on a plate containing the antibiotic, if they have the antibiotic resistance gene on the plasmid. The second is often a gene with a colour change, which is broken by the insertion of the fragment.

e.g. An example of a gene to test for the presence of a fragment is Green Fluorescent Protein (GFP) glowing or not. What would a bacterial plate look like that contained an antibiotic, and was spread with bacteria which had been transformed with a plasmid and had a new gene fragment in?

What substances can be used to take mature, differentiated adult cells, and de-differentiate them back into pluripotent stem cells ?(usually only found in embryos).

Where is the oestrogen receptor located?

Oestrogen can act as a transcription factor. To do so, it needs to bind to what molecule?

Where are transcription factors often stored?

The mRNA travels to the ribosome, where it feeds between the two subunits, exposing the template bases. tRNA molecules each carry a specific amino acid at the top, with a complementary sequence of three bases called an anti-codon at the bottom. The tRNA anticodons then complementary base pair with the mRNA codon.

In the ribosome there are 3 binding sites for tRNA, two where a peptide bond is formed between the carried amino acids. These amino acids then form a polypeptide chain which leaves the ribosome. The third site is a departure site, where the tRNA which has released its amino acid departs to pick up a new amino acid. Once the entire mRNA sequence has been ____11____, it can either pass into another ribosome to make another polypeptide or be degraded.

What is the difference between mRNA and pre-mRNA?

Which molecule is created during transcription?

If hypomethylation (reduced methylation) happens to a proto-oncogenes gene, what effect will this have on the rate of mitosis ?

Methylation of DNA is when a methyl group ( CH3) is added onto CpG bases ( cytosine and guanine next to each other). This can stop DNA polymerase from binding.

What effect will increased methylation (Hypermethylation) have on transcription?

Cancer is often caused by a mutation causing a cell to divide uncontrollably and spread into other tissues. Name the gene that normally slows or reduces cell division:

Fill in the missing word : Causes of Mutations A mutation is any change to the order of __12___ in the genetic code. These occur naturally as the enzyme _____13_____ replicates the DNA and makes mistakes. The incidence can also be produced due to exposure to certain agents called mutagenic agents. These can be chemicals such as nitrous acid, which converts cytosine to uracil.

Nitrous acid would therefore cause a __14___ mutation. Ethidium Bromide is used to stain DNA during gel electrophoresis. It can insert between bases, acting in a similar way to an addition mutation and therefore causing a __15___ along the rest of the gene. UV radiation is also a mutagenic agent.

It can cause bonds to form between pyrimidine bases ( thymine and cytosine). This bonding causes polymerases to misread or stop working all together at that point.

Fill in the missing word : Causes of Mutations A mutation is any change to the order of __12___ in the genetic code. These occur naturally as the enzyme _____13_____ replicates the DNA and makes mistakes. The incidence can also be produced due to exposure to certain agents called mutagenic agents.

These can be chemicals such as nitrous acid, which converts cytosine to uracil. Nitrous acid would therefore cause a __14___ mutation. Ethidium Bromide is used to stain DNA during gel electrophoresis. It can insert between bases, acting in a similar way to an addition mutation and therefore causing a __15___ along the rest of the gene.

UV radiation is also a mutagenic agent. It can cause bonds to form between pyrimidine bases ( thymine and cytosine). This bonding causes polymerases to misread or stop working all together at that point.

What type of mutation causes a sequence of bases to be moved from one location to another?

TTA = Leu TTG = Leu TTC = Phe TCA = Ser TAA = Stop Here is the original sequence : TTCTTGTTATCATAA. Here is a mutated sequence: TTCTTGTTATAACATAA.

What will be the effect on the mutated polypeptide?

TTA = Leu TTG = Leu TTC = Phe TCA = Ser TAA = Stop Here is the original sequence : TTCTTGTTATCATAA. Here is a mutated sequence: TTCTTATTATCATAA.

Will this mutation affect the primary structure of the polypeptide ?

What does the term 'Degenerate' mean when referring to the genetic code?

Name the type of bond that holds the complementary base pairs together.

Which component of a nucleotide contains nitrogen atoms?