Where is ribosomal RNA synthesised within the nucleus?

In the nucleolus, a dense region within the nucleus.

What are the functions of smooth endoplasmic reticulum?

Lipid synthesis and detoxification; it lacks ribosomes.

What is the main function of mitochondria in eukaryotic cells?

They are the sites of aerobic respiration and ATP production.

Edexcel A-Level Biology A 9BN0

Lifestyle, Health and Risk

Topic overview Water and the carbohydrates Condensation, hydrolysis and glycosidic bonds Lipids, food tests and units The cardiac cycle and the structure of the heart Arteries, veins and capillaries Core practical: caffeine and the heart rate of Daphnia The blood clotting cascade Thrombus, embolus and their consequences Atherosclerosis and the risk factors for CVD Treatments for CVD, and cholesterol transport BMI, waist-to-hip ratio and energy balance Core practical 2: the vitamin C content of food and drink Correlation, causation and the design of health studies Risk perception, and handling quantitative data

Genes and Health

Topic overview Gas exchange surfaces and Fick's Law The fluid mosaic model of the cell membrane Osmosis, diffusion and active transport Surface area and volume calculations The structure of DNA and RNA Transcription Translation and the genetic code Amino acids and the levels of protein structure Globular and fibrous proteins: haemoglobin and collagen Alternative splicing and tissue-specific proteins Enzyme specificity, the active site and activation energy Rates of reaction, Vmax and Core Practical 4 Semi-conservative replication and Meselson-Stahl Types of mutation and the CFTR gene Alleles, genotype and monohybrid inheritance Pedigree diagrams and the inheritance of cystic fibrosis The effects of cystic fibrosis, and the chi-squared test Prenatal genetic testing: PGD, amniocentesis and CVS The ethics of genetic screening

Voice of the Genome

Topic overview Prokaryotic cells Eukaryotic organelles and their functions Identifying organelles in an electron micrograph Protein secretion, and levels of organisation Microscopy: the graticule, magnification and standard form The cell cycle and the stages of mitosis Core practical: the root tip squash Meiosis, linkage and sex linkage The structure of sperm and egg cells Fertilisation: the acrosome and cortical reactions Totipotency, pluripotency and sources of stem cells The ethics and risks of stem cell therapy Differential gene expression and specialisation The lac operon Epigenetics: DNA methylation and histone modification Polygenic inheritance, continuous variation and statistics

Biodiversity and Natural Resources

Topic overview Biodiversity, species richness and the index of diversity Niches and the three kinds of adaptation Natural selection and evolution The Hardy-Weinberg equation and its assumptions Reproductive isolation and speciation Classification The plant cell wall, chloroplast and amyloplast The vacuole, plasmodesmata, pits and middle lamella Plant cells in the electron microscope Starch and cellulose Lignin, xylem vessels and sclerenchyma fibres Identifying plant tissues under the microscope The structure of xylem, phloem and sclerenchyma Water and the mineral nutrition of plants Core practical: investigating mineral deficiency Core practical: the tensile strength of plant fibres Drug development from Withering to modern trials Growing bacteria and aseptic technique Core practical: the antimicrobial properties of plants Sustainability and Conservation

On the Wild Side

Immunity, Infection and Forensics

Topic overview Decomposition, succession and forensic entomology Body cooling and rigor mortis DNA profiling and the polymerase chain reaction Gel electrophoresis The structure of bacteria and viruses Decomposition, and how pathogens enter the body The body's barriers, and modelling bacterial growth Tuberculosis and HIV The non-specific immune response Antigens, antibodies and B cells T cells and cell-mediated immunity Active and passive immunity, natural and artificial The evolutionary race and pathogen evasion Antibiotics and testing their effectiveness Hospital acquired infections and their control

Run for Your Life

Topic overview Muscles and Movement The myofibril and the sarcomere The sliding filament theory, calcium and ATP Slow-twitch and fast-twitch muscle fibres Glycolysis and the link reaction The Krebs cycle, oxidative phosphorylation and oxygen debt The conduction system: SAN, AVN and Purkyne fibres The sequence of cardiac excitation The electrocardiogram, cardiac output and stroke volume The cardiovascular and ventilation control centres Spirometry and ventilation during exercise Homeostasis, feedback and gene control by hormones Thermoregulation and the hypothalamus The effects of too much and too little exercise Medical technology and performance-enhancing substances

Grey Matter

Topic overview The structure of neurones and myelination The action potential and saltatory conduction The structure of a synapse and calcium entry Neurotransmitter release and acetylcholine Rod cells and the detection of light Effectors, the neuromuscular junction and the pupil reflex Phytochrome and the response to light IAA, phototropism and gravitropism Nervous against hormonal coordination The regions of the brain and their functions Brain imaging: MRI, fMRI, PET and CT Critical periods and the Hubel and Wiesel experiments Nature, nurture, habituation and research ethics Dopamine, serotonin and their imbalance L-Dopa and MDMA Genome sequencing, personalised medicine and its ethics Genetically modified organisms: benefits and risks

Voice of the Genome

Eukaryotic organelles and their functions

3 things to know
Papers 1, 2 and 3

Overview

Recall questions on the nucleus, ribosomes, endoplasmic reticulum, mitochondria, lysosomes, centrioles and the Golgi apparatus.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is the nucleus in a eukaryotic cell?

Key term

State the size and function of eukaryotic ribosomes.

Key term

What distinguishes rough endoplasmic reticulum from smooth ER, and what is its function?

Questions from this subtopic

Each one with the model answer underneath.

1
What is the nucleus in a eukaryotic cell?
Model answer
A membrane-bound organelle that houses the genetic material.
2
Where is ribosomal RNA synthesised within the nucleus?
Model answer
In the nucleolus, a dense region within the nucleus.
3
State the size and function of eukaryotic ribosomes.
Model answer
Eukaryotic ribosomes are 80S and are the sites of protein synthesis.
4
What distinguishes rough endoplasmic reticulum from smooth ER, and what is its function?
Model answer
Rough ER is studded with ribosomes and is involved in protein synthesis and transport.
5
What are the functions of smooth endoplasmic reticulum?
Model answer
Lipid synthesis and detoxification; it lacks ribosomes.
6
What is the main function of mitochondria in eukaryotic cells?
Model answer
They are the sites of aerobic respiration and ATP production.

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