Biology a level f215

Atomic structure in terms of the numbers of protons, neutrons and electrons for atoms and ions, given the atomic number, mass number and any ionic charge. Appreciate how the understanding of atom has evolved over time. An atomic structure in terms of a nucleus containing protons and neutrons surrounded by electrons.

Biology a level f215

Those with two different alleles for the same gene 71 of What does the mutation in CF do? Disrupts the transport of chloride ions and water across the membranes of cells lining the airways, gut and reproductive tract. It changes the shape of the transmembrane chloride ions so that they can no longer function effectively.

The Phenotype What are Alleles called if they both contrubute to the phenotype? Codominant When is an allele said to be dominant? If it is always expressed in the phenotype 75 of Refers to two or more genes that are located on the same chromosome,normally inherited together 76 of What is Sex Linkage?

Where the gene that codes for a charcteristic is only found on one of the sex chromosomes 77 of What does Sickle-cell anaemia cause? When abnoral haemoglobin is deoxygenated it is not soluble and becomes crstalline and aggregates into more linear and less globular structures, this deforms red blood cells making them inflexible and unable to sqeeze through the capillaries.

After many cycles of oxygenation and deoxygenation, some cells become irreversibly sickled, some are destroyedblood flow is impededorgans can become damaged 79 of What is Epistasis? The interaction of different gene loci so that one gene locus masks or supresses the expression of another gene locus 80 of How may the genes involved in Epistasis work?

Antagonistically or together in a complementary fashion 81 of What is hypostatic? Where the alleles at the first locus are epistatic to the alleles at the second locus 82 of No, but it reduces phenotypic variation 83 of When does dominant epistasis occur?

N-1 What does discontinuous variation describe? Quantitative differences between the phenoypes, no distinct categories, wide range of variation within the population 90 of When there is only one gene involed - discontinous variation 91 of Describe discontinuous varation? Different alleles at a single gene locus have large effects on the phenotype, different gene loci have quite different effects on the phenotype, different gene loci have quite different effects on the phenotype 92 of Describe continous variation?

One that is controlled by polygenes, genes are unlinkedthey are on different chromosomes 94 of which traits, poygenic or monogenic, are influenced the most by the environment?

Polygenic 95 of What is a population? All of the organisms of one species, who live in the same place at the same time, and who can breed together 96 of What is the gene pool?

The set of information carried by a population 97 of What does the Hardy-Weinberg principle measure? The genetic diversity of alleles of an individual 98 of What did Darwin deduce? That there is a competitve struggle for survival, there is varaition between individuals, those best adapted are more likely to survive and breed 99 of The study of gene pools and the allele and genotype frequencies of populations of organsims of What is the Hardy-Weinberg principle?

The concept that both genotype frequencies and gene frequencies will stay consatnt from generation to generation, within a large interbreeding population where mating is random, there is no mutationno selection or migration of what assumptions does the Hardy-Weinberg principle make? The population is very large eliminates sampling errormating is random, no selective advantage for any genotype, no mutation,migration or genetic drift of The frequency of the dominant allele of the frequency of the recessive genotype of What is a selection pressure?

An environmental factor that confers greater chances of survival to reproductive age on some members of the population of What is the carrying capacity of a population? The maximum population size that can be maintained over a period of time in a particular habitat of The combined action of biotic and abiotic factors that limits the growth of a population of non-living components of the environment of What is stabilising selection?

A type of natural selection in which the allele and genotpye frequency within populations stays the same because organisms are well adapted to their environment of What is directional selection?

A group of organisms that have similar morphology shapephysiology biochemistryembryology stages of development and behaviour and occupy the same niche of Whats is a group that includes an ancestral organism and all its descendant species called?

A monophylectic group of When is the biological species concept problematic?OCR A Level Biology F STUDY. PLAY. Gene. A length of DNA that codes for one or more polypeptides.

Polypeptide. A polymer consisting of a chain of amino acid residues joined by peptide bonds. Genome. The entire DNA sequence of an organism.

Biology a level f215

Protein. A large polypeptide, usually or more amino acids. Past papers, summary notes and past exam questions by topic for OCR Biology A-Level Unit 5 (F). This guide contains the details of over 5, databases or "systems of records" in which the US Government maintains information on individuals.

Complete knowledge & practice of AS/A2 Chemistry topic on Atomic Structure & The Changing Models of Atom with exam questions & solution. AS/A Level GCE - Biology A - H, H (from ) AS/A Level GCE - Biology B (Advancing Biology) - H, H (from ) This specification has been written for students who wish to continue their study of Biology after GCSE.

A PPT originally adapted for IGCSE Biology. Presentation on relationships of organisms with one another and with their environment.

Biology a level f215
OCR Unit 5 (F) Biology Revision - Physics & Maths Tutor