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40 Cards in this Set
- Front
- Back
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What is inter specific variation |
Variation within different species |
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What is intrespecific variation |
Variation within the same species |
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Why may sampling not be representative of a population |
Sampling bias- invested intrests Chance |
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What are 3 ways to reduce sample bias |
Choose a larger sample size so there is less of a probability of chance influence Use random sampling Analyse the data with statistical tests |
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What three things lead to genetic differences |
Meiosis Fusion of gametes Mutation |
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What is the name of the amount of chromosomes in gametes |
The haploid number |
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When and how does crossing over occur in meiosis |
During the first division chromatids wrap around their homologous pair and swap genes |
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How does meiosis cause genetic variation |
Recombination of homologous pairs by crossing over and also the independent segregation of homologous chromosomes |
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What is a gene |
A section of DNA that codes for a polypeptide |
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That is a locus in terms of DNA |
The position of a gene on a DNA molecule |
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Describe the independent segregation of homologous chromosomes |
The homologous pairs will line up randomly thus the combination of paternal and maternal chromosomes is random |
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What are the four requirements for semi-conservative replication |
All four types of nucleotide must be present Both strands of DNA - templates for new strands DNA polymerase must catalyse the reaction Chemical energy source to drive the process |
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Describe the process of semi-conservative replication |
DNA helicase breaks the hydrogen bonds linking base pairs so the double helix separates into two strands. Each exposed polynucleotide attaches to a complementary free nucleotide and energy is given to activate the nucleotides. Then DNA polymerase join together the activated nucleotides |
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What is the conservative DNA model |
Where one DNA molecule is completely formed of parental DNA whilst the other is newly built up of free nucleotides. |
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What is the test for semi-conservative DNA |
All DNA bases contain nitrogen an there are two isotopes of this N13 and N14. Bacteria will incorporate the nitrogen in their environment into their DNA by this we can track parental DNA concentration in different generations of bacteria |
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What features enable terrestrial organisms to conserve water |
Small SA:V ratios with waterproof coverings on their skin |
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What two features do insects have to reduce water loss |
A small surface area and waterproof coverings |
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Describe how diffusion gradients cause air to move through an insects tracheal system |
Along a diffusion gradient where at one end of the trachioles oxygen is being used up in respiring tissue and the creation of CO2 leads to another diffusion gradient in the opposite direction |
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Describe how ventilation causes air to move through an insects tracheal system
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The movement of muscles in insects create mass movements of air in an out of the trachioles which speeds up exchange |
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Why are spiracles controlled by valves |
So water cannot evaporate out of them |
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Why is the tracheal system limiting on the evolution of insects |
They can only grow to a maximum size as the diffusion pathway must be short since this system relies on diffusion |
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Describe the levels of oxygen in the tracheae when the spiracles are closed |
The oxygen begins to decrease as it is used up in respiration |
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What causes the spiracles to open |
An increasing level of carbon dioxide |
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What are at right angles to the gill filaments and what do they do |
Gill lamellae- increase surface area for diffusion |
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Describe the countercurrent flow in fish |
Blood with plenty of oxygen meets water which has its maximum concentration of oxygen so diffusion of oxygen occurs. Blood with little oxygen meets water with little oxygen. This system favours diffusion from the water to the blood |
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Describe the adaptations that allow plants to rely on diffusion for gas exchange |
Thin flat leaves Stomata Interconnecting air spaces throughout the mesophyll |
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Why at some light intensities may carbon dioxide be neither taken in or given out a plant |
The volume of carbon dioxide taken in during photosynthesis is the same as the volume given out by respiration |
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Whether an organism has a specialised transport system depends on 2 things |
The SA:V How active the organism is |
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What are 6 features of a transport system i.e the blood |
A medium to carry materials-blood A form of mass transport A closed system of tubular vessels containing the transport medium A mechanism for moving the medium within the vessels A mechanism to maintain the flow direction A means of changing the flow to suit the changing needs of the organism |
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Why may a transport medium e.g. blood be water based |
Water is a solvent and can be moved around easily |
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What feature of a transport system is the cardiovascular vessel network |
A closed system of branched tubular vessels to distribute the transport medium |
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What feature of a transport system is the heart or cohesive forces and evaporation |
A mechanism for moving the transport medium |
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What feature of a transport medium are valves |
Mechanisms to maintain the direction of the mass flow of the transport medium |
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Why is the circulatory system double pumped |
In order to re-increase the blood pressure and maintain the speed of blood flow to tissues |
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Which vessels carry blood to the liver from the heart |
Aorta > Hepatic artery |
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What vessel carries blood to the liver from the stomach and intestines |
Hepatic portal artery |
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What vessels carry blood from the liver to the heart |
Hepatic vein > Vena Cava |
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What vessels carry blood from the heart to the kidneys |
Aorta > Renal Artery |
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What vessels carry blood from the kidneys to the heart |
Renal Vein > Vena Cava |
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Describe the structure of arteries |
Thick muscle layer to |
