Lessons

Last Accessed

Recently visited lessons will appear here after you sign in.

Common to Papers 1 and 2

Topic 1 - Key concepts in biology

1.1 - Cell structures and functions

1.2 - Specialised cells

1.3 - 1.5 - Microscopy, scale and units

1.6 - Microscopy practical

1.7 - 1.9 - Enzyme action and conditions

1.10 - 1.11 - Investigating enzyme activity

1.12 - Building and breaking molecules

1.13B - Food tests

1.14B - Food calorimetry

1.15 - Cell transport

1.16 - 1.17 - Osmosis practical

Paper 1

Topic 2 - Cells and control

2.1 - 2.4 - Mitosis and cell division

2.5 - 2.7 - Growth and differentiation

2.8 - 2.9 - Stem cells

2.10B - Brain structure and function

2.11B - 2.12B - Brain imaging and treatment

2.13 - 2.14 - Nerves, synapses and reflex arcs

2.15B - How the eye works

2.16B - 2.17B - Vision defects and correction

Topic 3 - Genetics

3.1B - 3.3 - Reproduction and meiosis

3.4 - 3.5 - DNA, genes and genomes

3.6 - Extracting DNA from fruit

3.7B - 3.8B - Protein synthesis

3.9B - 3.10B - Genetic variants and proteins

3.11B - 3.13 - Mendel and inheritance terms

3.14 - 3.16 - Genetic crosses and pedigrees

3.17B - ABO blood-group inheritance

3.18B - Sex-linked inheritance

3.19 - 3.20 - Variation

3.21 - The Human Genome Project

3.22 - 3.23 - Mutation

Topic 4 - Natural selection and genetic modification

4.1B - 4.3 - Natural selection and resistance

4.4 - 4.5 - Evidence for human evolution

4.6B - 4.7 - Evolutionary relationships and classification

4.8 - Selective breeding

4.9B - Tissue culture

4.10 - Genetic engineering

4.11 - Genetic engineering methods

4.12B - GM crops

4.13B - Agriculture and food demand

4.14 - Biotechnology choices

Topic 5 - Health, disease and the development of medicines

5.1 - 5.4 - Health, disease and pathogens

5.5 - 5.6 - Infection spread

5.7B - Viral lifecycles

5.8 - Sexually transmitted infections

5.9B - 5.10B - Plant defences

5.11B - Identifying plant disease

5.12 - Human barriers and defences

5.13 - 5.15B - Immune response and vaccination

5.16 - 5.19B - Antibiotics and antimicrobial practical

5.20 - Developing medicines

5.21B - Producing monoclonal antibodies

5.22B - Using monoclonal antibodies

5.23 - 5.24 - Lifestyle and disease risk

5.25 - Cardiovascular treatments

Paper 2

Topic 6 - Plant structures and their functions

6.1 - 6.2 - Photosynthesis

6.3 - 6.4 - Limiting factors

6.5 - Photosynthesis practical

6.6 - Inverse square law

6.7 - 6.10 - Plant transport systems

6.11B - Leaf structure

6.12 - 6.13 - Water uptake and rates

6.14B - Plants in extreme environments

6.15B - Auxin and tropisms

6.16B - Commercial uses of plant hormones

Topic 7 - Animal coordination, control and homeostasis

7.1 - The endocrine system

7.2 - Adrenalin and fight or flight

7.3 - Thyroxine and feedback

7.4 - 7.5 - The menstrual cycle

7.6 - 7.7 - Contraception

7.8 - Fertility treatment

7.9 - 7.10B - Why homeostasis matters

7.11B - 7.12B - Thermoregulation

7.13 - 7.14 - Blood glucose control

7.15 - 7.16 - Diabetes

7.17 - Body mass and diabetes risk

7.18B - 7.19B - Kidneys and urine formation

7.20B - ADH and water balance

7.21B - 7.22B - Urea and kidney failure

Topic 8 - Exchange and transport in animals

8.1 - 8.2 - Exchange and transport needs

8.3 - 8.5B - Alveoli and diffusion

8.6 - Blood and its components

8.7 - Blood vessels

8.8 - The heart and circulation

8.9 - 8.10 - Cellular respiration

8.11 - Measuring respiration

8.12 - Cardiac output calculations

Topic 9 - Ecosystems and material cycles

9.1 - 9.4 - Ecosystem organisation and interdependence

9.5 - 9.6 - Fieldwork with quadrats and transects

9.7B - 9.8B - Biomass and energy transfer

9.9 - 9.10 - Human impacts and biodiversity

9.11B - Food security

9.12 - 9.13 - Material cycling and carbon

9.14 - Water cycle and water supply

9.15 - Nitrogen cycle and farming

9.16B - Pollution indicators

9.17B - 9.19B - Decomposition and decay rates

3.17B - ABO blood-group inheritance

3.17B - ABO blood-group inheritance

Extend simple genetic crosses to a gene with three alleles in the population. Use ABO blood groups to distinguish codominance from dominance and work out which blood groups offspring could inherit.

3.17B — ABO blood-group inheritance

Biology-only (Foundation and Higher): 3.17B

The ABO blood-group gene shows two features that extend the ordinary two-allele, complete-dominance model.

Multiple alleles means that more than two alleles of one gene exist in the population. The main ABO alleles are $I^A$ , $I^B$ and $I^o$ . A person still inherits only two alleles, one from each parent.

Codominance means that two different alleles are both expressed in a heterozygote. $I^A$ and $I^B$ are codominant with each other, so $I^A I^B$ produces blood group AB rather than A, B or a blended intermediate. The $I^o$ allele is recessive to both $I^A$ and $I^B$ .

Genotype	Blood-group phenotype
$I^A I^A$	A
$I^A I^o$	A
$I^B I^B$	B
$I^B I^o$	B
$I^A I^B$	AB
$I^o I^o$	O

Worked example: producing all four blood groups

A parent with heterozygous group A has genotype $I^A I^o$ . A parent with heterozygous group B has genotype $I^B I^o$ .

Continue this lesson.

You’re previewing NovaLearn without an account. Create a free account to read the rest.

Create free account