Science (Double Award) — Modular 2024, Biology Unit 1

Science 4XSD1 — specification explorer

All 74 specification statements from the official Pearson Edexcel specification, as printed — filter by paper, unit or tier exactly as Pearson Edexcel assesses them.

Scope the specification

74 spec points

Unit

Assessment homes come from the parsed Pearson specification (content summaries & assessment overviews). Hover a chip for the printed rule. Filters appear only where the qualification has that structure — a linear IGCSE has no unit scope, and only Maths A splits Foundation / Higher tiers.

1. The nature and variety of living organisms

1. Characteristics of living organisms

1.1
understand how living organisms share the following characteristics:
- they require nutrition
- they respire
- they excrete their waste
- they respond to their surroundings
- they move
- they control their internal conditions
- they reproduce
- they grow and develop.
Unit 1

2. Variety of living organisms

1.2describe the common features shown by eukaryotic organisms: plants, animals, fungi and protoctists Plants: these are multicellular organisms; their cells contain chloroplasts and are able to carry out photosynthesis; their cells have cellulose cell walls; they store carbohydrates as starch or sucrose. Examples include flowering plants, such as a cereal (for example maize) and a herbaceous legume (for example peas or beans). Animals: these are multicellular organisms; their cells do not contain chloroplasts and are not able to carry out photosynthesis; they have no cell walls; they usually have nervous co- ordination and are able to move from one place to another; they often store carbohydrate as glycogen. Examples include mammals (for example humans) and insects (for example housefly and mosquito). Fungi: these are organisms that are not able to carry out photosynthesis; their body is usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei; some examples are single-celled; their cells have walls made of chitin; they feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products; this is known as saprotrophic nutrition; they may store carbohydrate as glycogen. Examples includeMucor, which has the typical fungal hyphal structure, and yeast, which is single-celled.Unit 1
1.3describe the common features shown by prokaryotic organisms such as bacteria Bacteria: these are microscopic single-celled organisms; they have a cell wall, cell membrane, cytoplasm and plasmids; they lack a nucleus but contain a circular chromosome of DNA; some bacteria can carry out photosynthesis but most feed off other living or dead organisms. Examples includeLactobacillus bulgaricus, a rod-shaped bacterium used in the production of yoghurt from milk, andPneumococcus, a spherical bacterium that acts as the pathogen causing pneumonia.Unit 1
1.4understand the term ‘pathogen’ and know that pathogens may include fungi, bacteria, protoctists and viruses Viruses: these are not living organisms. They are small particles, smaller than bacteria; they are parasitic and can reproduce only inside living cells; they infect every type of living organism. They have a wide variety of shapes and sizes; they have no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA. Examples include the tobacco mosaic virus that causes discolouring of the leaves of tobacco plants by preventing the formation of chloroplasts, the influenza virus that causes flu and the HIV virus that causes AIDS.Unit 1

2. Structure and functions in living organisms: Part

1. Level of organisation

2.1describe the levels of organisation in organisms: organelles, cells, tissues, organs and systemsUnit 1

2. Cell structure

2.2describe cell structures, including the nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes and vacuoleUnit 1
2.3describe the functions of the nucleus, cytoplasm, cell membrane, cell wall, mitochondria, chloroplasts, ribosomes and vacuoleUnit 1
2.4know the similarities and differences in the structure of plant and animal cellsUnit 1

3. Biological molecules

2.7identify the chemical elements present in carbohydrates, proteins and lipids (fats and oils)Unit 1
2.8describe the structure of carbohydrates, proteins and lipids as large molecules made up from smaller basic units: starch and glycogen from simple sugars, protein from amino acids, and lipid from fatty acids and glycerolUnit 1
2.9practical: investigate food samples for the presence of glucose, starch, protein and fatUnit 1
2.10understand the role of enzymes as biological catalysts in metabolic reactionsUnit 1
2.11understand how temperature changes can affect enzyme function, including changes to the shape of active siteUnit 1
2.12practical: investigate how enzyme activity can be affected by changes in temperatureUnit 1
2.13understand how enzyme function can be affected by changes in pH altering the active siteUnit 1

4. Movement of substances into and out of cells

2.15understand the processes of diffusion, osmosis and active transport by which substances move into and out of cellsUnit 1
2.16understand how factors affect the rate of movement of substances into and out of cells, including the effects of surface area to volume ratio, distance, temperature and concentration gradientUnit 1
2.17practical: investigate diffusion and osmosis using living and non-living systemsUnit 1

5. Nutrition

2.18understand the process of photosynthesis and its importance in the conversion of light energy to chemical energyUnit 1
2.19know the word equation and the balanced chemical symbol equation for photosynthesisUnit 1
2.20understand how varying carbon dioxide concentration, light intensity and temperature affect the rate of photosynthesisUnit 1
2.21describe the structure of the leaf and explain how it is adapted for photosynthesisUnit 1
2.22understand that plants require mineral ions for growth, and that magnesium ions are needed for chlorophyll and nitrate ions are needed for amino acidsUnit 1
2.23practical: investigate photosynthesis, showing the evolution of oxygen from a water plant, the production of starch and the requirements of light, carbon dioxide and chlorophyllUnit 1
2.24understand that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibreUnit 1
2.25identify the sources and describe the functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre as components of the dietUnit 1
2.26understand how energy requirements vary with activity levels, age and pregnancyUnit 1
2.27describe the structure and function of the human alimentary canal, including the mouth, oesophagus, stomach, small intestine (duodenum and ileum), large intestine (colon and rectum) and pancreasUnit 1
2.28understand how food is moved through the gut by peristalsisUnit 1
2.29understand the role of digestive enzymes, including the digestion of starch to glucose by amylase and maltase, the digestion of proteins to amino acids by proteases and the digestion of lipids to fatty acids and glycerol by lipasesUnit 1
2.30understand that bile is produced by the liver and stored in the gall bladderUnit 1
2.31understand the role of bile in neutralising stomach acid and emulsifying lipidsUnit 1
2.32understand how the small intestine is adapted for absorption, including the structure of a villusUnit 1

6. Respiration

2.34understand how the process of respiration produces ATP in living organismsUnit 1
2.35know that ATP provides energy for cellsUnit 1
2.36describe the differences between aerobic and anaerobic respirationUnit 1
2.37know the word equation and the balanced chemical symbol equation for aerobic respiration in living organismsUnit 1
2.38know the word equation for anaerobic respiration in plants and in animalsUnit 1
2.39practical: investigate the evolution of carbon dioxide and heat from respiring seeds or other suitable living organismsUnit 1

7. Gas exchange

2.46describe the structure of the thorax, including the ribs, intercostal muscles, diaphragm, trachea, bronchi, bronchioles, alveoli and pleural membranesUnit 1
2.47understand the role of the intercostal muscles and the diaphragm in ventilationUnit 1
2.48explain how alveoli are adapted for gas exchange by diffusion between air in the lungs and blood in capillariesUnit 1
2.49understand the biological consequences of smoking in relation to the lungs and the circulatory system, including coronary heart diseaseUnit 1
2.50practical: investigate breathing in humans, including the release of carbon dioxide and the effect of exerciseUnit 1

3. Structure and functions in living organisms: Part

1. Transport

3.1understand why simple, unicellular organisms can rely on diffusion for movement of substances in and out of the cellUnit 2
3.2understand the need for a transport system in multicellular organismsUnit 2
3.3describe the role of phloem in transporting sucrose and amino acids between the leaves and other parts of the plantUnit 2
3.4describe the role of xylem in transporting water and mineral ions from the roots to other parts of the plantUnit 2
3.9describe the composition of the blood: red blood cells, white blood cells, platelets and plasmaUnit 2
3.10understand the role of plasma in the transport of carbon dioxide, digested food, urea, hormones and heat energyUnit 2
3.11understand how adaptations of red blood cells make them suitable for the transport of oxygen, including shape, the absence of a nucleus and the presence of haemoglobinUnit 2
3.12understand how the immune system responds to disease using white blood cells, illustrated by phagocytes ingesting pathogens and lymphocytes releasing antibodies specific to the pathogenUnit 2
3.15describe the structure of the heart and how it functionsUnit 2
3.16explain how the heart rate changes during exercise and under the influence of adrenalineUnit 2
3.17understand how specific factors may increase the risk of developing coronary heart diseaseUnit 2
3.18understand how the structure of arteries, veins and capillaries relates to their functionUnit 2
3.19understand the general structure of the circulation system, including the blood vessels to and from the heart and the lungs, the liver and the kidneysUnit 2

2. Excretion

3.20understand the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a leafUnit 2
3.21know the excretory products of the lungs, kidneys and skin (organs of excretion)Unit 2

3. Co-ordination and response

3.30understand how organisms are able to respond to changes in their environmentUnit 2
3.31understand that homeostasis is the maintenance of a constant internal environment, and that body water content and body temperature are both examples of homeostasisUnit 2
3.32understand that a co-ordinated response requires a stimulus, a receptor and an effectorUnit 2
3.33understand that plants respond to stimuliUnit 2
3.34describe the geotropic and phototropic responses of roots and stemsUnit 2
3.35understand the role of auxin in the phototropic response of stemsUnit 2
3.36describe how nervous and hormonal communication control responses and understand the differences between the two systemsUnit 2
3.37understand that the central nervous system consists of the brain and spinal cord, and is linked to sense organs by nervesUnit 2
3.38understand that stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responsesUnit 2
3.39understand the role of neurotransmitters at synapsesUnit 2
3.40describe the structure and functioning of a simple reflex arc, illustrated by the withdrawal of a finger from a hot objectUnit 2
3.41describe the structure and function of the eye as a receptorUnit 2
3.42understand the function of the eye in focusing on near and distant objects, and in responding to changes in light intensityUnit 2
3.43describe the role of the skin in temperature regulation, with reference to sweating, vasoconstriction and vasodilationUnit 2
3.44understand the sources, roles and effects of the following hormones: adrenaline, insulin, testosterone, progesterone and oestrogenUnit 2