Name the three alleles of the human ABO blood group gene and state their dominance relationships.

The alleles are Iᴬ, Iᴮ and Iᴼ; Iᴬ and Iᴮ are codominant with each other and both are dominant to Iᴼ.

List the genotypes that give each of the four ABO blood groups.

Group A is IᴬIᴬ or IᴬIᴼ, group B is IᴮIᴮ or IᴮIᴼ, group AB is IᴬIᴮ and group O is IᴼIᴼ.

What do the Iᴬ and Iᴮ alleles actually code for?

Each codes for a different enzyme that adds a different sugar to the H antigen on the erythrocyte surface, while Iᴼ codes for a non-functional enzyme so no extra sugar is added.

A man of blood group AB and a woman of blood group O have children. Which blood groups can the children be?

Every child will be group A or group B, in an expected 1 : 1 ratio, and none can be group AB or group O.

A blood group A parent and a blood group B parent are both heterozygous. State the expected ratio of blood groups among their children.

All four groups are expected, in a ratio of 1 group AB : 1 group A : 1 group B : 1 group O.

OCR A-Level Biology B H422

The Developing Cell: Cell Division and Cell Differentiation

Topic overview The cell cycle and mitosis Apoptosis in growth and repair Stem cells and cell differentiation

The Developing Individual: Meiosis, Growth and Development

Topic overview Meiosis, haploid gametes and genetic variation The stages of meiosis Antenatal care and diet in pregnancy Alcohol, smoking and monitoring fetal growth Prenatal screening and karyotypes

The Development of Species: Evolution and Classification

Topic overview Classification and the species concept Evidence for classification and DNA barcoding Phylogenetic trees, hominids and the evolution of language Human adaptations, natural selection and evolution Plant adaptations and how they are investigated Measuring biodiversity and genetic diversity

Cells and Microscopy

Topic overview Microscopy and the cell theory Blood smears, staining and microscope drawings Blood cells and their structure Magnification and measuring cells Haemocytometer cell counts and dilutions Flow cytometry in blood analysis Ultrastructure of the animal cell Plant and prokaryotic cells Membrane lipids and the fluid mosaic model Movement of molecules across membranes The roles of membranes and the secretion of proteins

Water and Its Importance in Plants and Animals

Topic overview The properties of water Water as a transport medium and the composition of body fluids Detecting and measuring sugars and proteins Monomers, polymers and the carbohydrates Osmosis and water potential

Proteins and Enzymes

Topic overview Amino acids, peptide bonds and chromatography Globular protein structure: enzymes and haemoglobin Enzyme action and the rate of reaction Blood clotting and first aid Enzymes and inhibitors in medicine Blood donation and stored blood products

Nucleic Acids

Topic overview Nucleotides, ADP and ATP The structure of DNA and its extraction DNA replication and the genetic code RNA, transcription and translation

Patterns of Inheritance

Topic overview Monogenic inheritance and genetic terminology Gene mutations and inherited disease Codominance, multiple alleles and linkage Model organisms, dihybrid crosses and the chi-squared test Chromosome mutations and genetic counselling

Population Genetics and Epigenetics

Topic overview Natural selection, sickle cell and malaria The Hardy-Weinberg principle Genetic drift, the founder effect and speciation Epigenetics and gene expression

Gene Technologies

Topic overview Post-Transcriptional Editing of mRNA Genetic modification of bacteria and insulin production The polymerase chain reaction and gel electrophoresis Haplotypes, SNPs, VNTRs and genetic engineering in eukaryotes Gene therapy and RNA interference

The Principles and Importance of Homeostasis

Topic overview Homeostatic principles, normal ranges and feedback The nervous and hormonal control of heart rate The control of body temperature and the role of thyroxine Measuring core body temperature, hypothermia and hyperthermia

The Hormonal Control of Blood Glucose and the Management of Diabetes

Topic overview The pancreas as an endocrine gland The regulation of blood glucose by negative feedback Types of diabetes and diagnostic testing Treating and managing diabetes

Kidney Functions and Malfunctions

Topic overview Excretion and the gross structure of the kidney The nephron: ultrafiltration and selective reabsorption Investigating the composition of urine, plasma and filtrate Osmoregulation and the action of ADH The kidney as an endocrine gland and kidney failure Dialysis, transplantation and the future of transplant surgery

The Cellular Basis of Cancer and Treatment

Topic overview Risk factors for non-communicable disease Cell cycle control and tumour formation Proto-oncogenes and tumour suppressor genes Epidemiological evidence, screening and genetic testing Methods used to detect cancer Treating patients with cancer

Respiratory Diseases and Treatment

Topic overview Pollutants and the respiratory system COPD, asthma and lung cancer Treating asthma and medicinal drugs from plants Clinical trials and the role of NICE

Cellular Respiration

Topic overview Glycolysis and the link reaction The Krebs cycle Oxidative phosphorylation and anaerobic respiration Respiratory substrates and respiratory quotients Measuring the rate of respiration

Metabolism and Exercise

Topic overview The consequences of exercise on the body Aerobic fitness and VO₂ max Training, F.I.T.T. factors and investigating fitness Enhancing athletic performance Haemoglobin and the transport of oxygen Oxygen dissociation curves of different respiratory pigments Oxygen deficit and oxygen debt The structure of skeletal muscle The sliding filament theory of muscle contraction

Pathogenic Microorganisms

Topic overview How pathogens cause communicable disease Tuberculosis HIV, AIDS and the structure of the virus Identifying bacteria: Gram staining and culture Epidemiology: incidence, prevalence and mortality Notifiable diseases and the control of HIV and TB

The Immune System

Topic overview Primary defences and non-specific responses B and T lymphocytes and the specific response Antibodies and testing for TB and HIV Types of immunity and allergy

Controlling Communicable Diseases

Topic overview Vaccination and vaccination programmes Problems and ethics of vaccine development and use Antibiotics and antibiotic resistance Investigating antibiotics, disinfectants and hygiene

Photosynthesis, Food Production and Management of the Environment

Topic overview Chloroplast ultrastructure and photosynthetic pigments The light-dependent stage of photosynthesis The Calvin cycle Investigating the factors affecting photosynthesis The Hill reaction and DCPIP Using TP and GP to build carbohydrates, lipids and amino acids The compensation point and crop production Microorganisms, the nitrogen cycle and biosensors Biomass transfer and efficiency in food production Ruminants in the human food chain Farms as ecosystems and the conflict with conservation Deflected succession and measuring biodiversity

The Impact of Population Increase

Topic overview Birth rate, death rate and demographic change Human impact on ecosystems and biodiversity The importance and measurement of species biodiversity Global food security and sustainable food production

Planning and Implementing Practical Work

Topic overview Designing an investigation and controlling variables Choosing apparatus and judging whether a method will work Implementing: apparatus, units and recording results

Analysing and Evaluating Practical Results

Topic overview Processing and interpreting experimental results Mathematical skills for analysing biological data Significant figures and reporting values Plotting and interpreting graphs Anomalies, limitations and refining a procedure Precision, accuracy and uncertainty

Practical Skills, Apparatus and Techniques

Topic overview Investigative approaches and working safely Following instructions, recording and presenting data Research, referencing and processing data with software Measuring mass, volume, time, temperature, length and pH Colorimeters and potometers Laboratory glassware and serial dilutions Light microscopy, graticules and biological drawing Qualitative reagents for biological molecules Chromatography and electrophoresis Aseptic technique and dissection Whole-organism responses, fieldwork sampling and data logging

Fertility and Assisted Reproduction

Topic overview The urinogenital systems and gonad histology Gametogenesis and the structure of the gametes Hormonal control of gametogenesis and the menstrual cycle Fertilisation and pregnancy testing The causes and issues of infertility Assisted reproduction techniques

The Effects of Ageing on the Reproductive System

Topic overview Ageing and the female reproductive system Managing the menopause Ageing and the male urinogenital system

Plant Reproduction

Topic overview The control of flowering Adaptations of flowers for pollination Fertilisation, seed formation and germination Cereals as staple foods

The Nervous System and the Identification and Consequences of Damage

Topic overview Organisation of the nervous system and nervous tissue The structure and function of the human brain The structure of motor, sensory and relay neurones Resting potential and the action potential Synapses and the integration of responses Reflexes, reaction times and their investigation Brain scans and the consequences of nervous system damage Drugs, brain function and dependency

Monitoring Visual Function

Topic overview The structure of the eye The retina and its role as a transducer Assessing visual function by routine eye tests

The Effect of Ageing on the Nervous System

Topic overview Alzheimer's disease: symptoms and causes The effects of ageing on the senses and memory Investigating ageing, reaction times and memory

The Heart and Monitoring Heart Function

Topic overview The need for a mass transport system Structure and dissection of the mammalian heart The cardiac cycle Initiation and coordination of the heartbeat Heart rate, pulse rate and cardiac output Electrocardiograms and emergency cardiac treatment

Transport Systems in Mammals

Topic overview The closed double circulatory system Blood vessels and their microscopic structure Tissue fluid and capillary exchange Measuring and interpreting blood pressure

Gas Exchange in Mammals and Plants

Topic overview Tissues of the mammalian gas exchange system Gas exchange in the alveoli Pulmonary ventilation and lung volumes Expired air resuscitation Gas exchange and stomata in terrestrial plants

Transport Systems in Plants

Topic overview The need for transport systems in plants Vascular tissue in roots, stems and leaves Water uptake and movement through the plant Transpiration and Its Measurement Translocation in the Phloem

Patterns of Inheritance

Codominance, multiple alleles and linkage

3 things to know
Components 01, 02 and 03

Overview

Recall questions on multiple alleles and the Iᴬ, Iᴮ and Iᴼ alleles, ABO genotypes and crosses, codominant HLA antigens on chromosome 6 and transplant matching, sex linkage and haemophilia, and autosomal linkage, nail-patella syndrome and recombinant percentages.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Why is haemophilia far commoner in males than in females?

Key term

The gene for nail-patella syndrome lies close to the ABO blood group gene on the same chromosome. What does this mean within an affected family?

Key term

What is meant by multiple alleles?

Questions from this subtopic

Each one with the model answer underneath.

1
What is meant by multiple alleles?
Model answer
More than two alleles of a gene exist in the population, although any one diploid individual can carry only two of them.
2
Name the three alleles of the human ABO blood group gene and state their dominance relationships.
Model answer
The alleles are Iᴬ, Iᴮ and Iᴼ; Iᴬ and Iᴮ are codominant with each other and both are dominant to Iᴼ.
3
List the genotypes that give each of the four ABO blood groups.
Model answer
Group A is IᴬIᴬ or IᴬIᴼ, group B is IᴮIᴮ or IᴮIᴼ, group AB is IᴬIᴮ and group O is IᴼIᴼ.
4
What do the Iᴬ and Iᴮ alleles actually code for?
Model answer
Each codes for a different enzyme that adds a different sugar to the H antigen on the erythrocyte surface, while Iᴼ codes for a non-functional enzyme so no extra sugar is added.
5
A man of blood group AB and a woman of blood group O have children. Which blood groups can the children be?
Model answer
Every child will be group A or group B, in an expected 1 : 1 ratio, and none can be group AB or group O.
6
A blood group A parent and a blood group B parent are both heterozygous. State the expected ratio of blood groups among their children.
Model answer
All four groups are expected, in a ratio of 1 group AB : 1 group A : 1 group B : 1 group O.

See the rest and revise

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book

2Open book

3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

The Developing Cell: Cell Division and Cell Differentiation

The Developing Individual: Meiosis, Growth and Development

The Development of Species: Evolution and Classification

Cells and Microscopy

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

measles and .

tuberculosismalariacholera

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

ABrain tissue is metabolically expensive.

BA high-quality diet is needed to sustain it.

CThe large head makes birth difficult.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Core body temperature is normally about 37 °C.

TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Patterns of Inheritance, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Start revising, £5 a month See how the method works

Or £46 a year, about £3.83 a month. Cancel anytime.