All Topics
biology-0610-core | cambridge-igcse
Your Flashcards are Ready!
15 Flashcards in this deck.
1.
Plant Nutrition
2.
Gas Exchange in Humans
3.
Reproduction
4.
Human Nutrition
5.
Respiration
6.
Characteristics and Classification of Living Organisms
7.
Inheritance
8.
Excretion in Humans
9.
Transport in Plants
10.
Coordination and Response
11.
Organisation of the Organism
12.
Variation and Selection
13.
Movement into and out of Cells
14.
Transport in Animals
15.
Organisms and Their Environment
16.
Biological Molecules
17.
Drugs
18.
Human Influences on Ecosystems
19.
Diseases and Immunity
20.
Enzymes
21.
Biotechnology and Genetic Modification
Functions and sources of carbohydrates, proteins, fats, vitamins, minerals, water, fiber
Topic 2/3
or
3
Still Learning
I know
12
Previous
Next
Functions and Sources of Carbohydrates, Proteins, Fats, Vitamins, Minerals, Water, Fiber
Introduction
Nutrients are essential substances required by the human body to sustain life, support growth, and maintain overall health. In the Cambridge IGCSE Biology curriculum, understanding the functions and sources of carbohydrates, proteins, fats, vitamins, minerals, water, and fiber is fundamental. This knowledge not only underpins the principles of human nutrition but also provides insights into maintaining a balanced diet and preventing nutritional deficiencies.
Key Concepts
Carbohydrates
Carbohydrates are organic compounds composed of carbon, hydrogen, and oxygen, typically with a hydrogen:oxygen atom ratio of 2:1. They are classified into three main types: monosaccharides, disaccharides, and polysaccharides.
- Monosaccharides: The simplest form of carbohydrates, consisting of single sugar molecules like glucose and fructose.
- Disaccharides: Formed by the linkage of two monosaccharides, such as sucrose (table sugar) and lactose (milk sugar).
- Polysaccharides: Complex carbohydrates made up of many monosaccharide units. Examples include starch, glycogen, and cellulose.
- Simple Carbohydrates: Fruits, table sugar, honey, and dairy products.
- Complex Carbohydrates: Whole grains, legumes, vegetables, and potatoes.
Proteins
Proteins are large, complex molecules made up of amino acids linked by peptide bonds. There are 20 different amino acids that combine in various sequences to form proteins.
Function:
Proteins are essential for numerous biological functions:
- Structural Components: Form structures like muscles, skin, and hair.
- Enzymes: Catalyze biochemical reactions.
- Hormones: Regulate physiological processes (e.g., insulin).
- Immune Function: Act as antibodies to fight pathogens.
- Transport and Storage: Carry molecules like oxygen (hemoglobin).
- Animal Sources: Meat, fish, eggs, and dairy products.
- Plant Sources: Legumes, nuts, seeds, and certain grains like quinoa.
Fats
Fats, or lipids, are hydrophobic molecules composed mainly of carbon, hydrogen, and oxygen. They include triglycerides, phospholipids, and steroids.
Function:
Fats serve multiple roles in the body:
- Energy Storage: Provide a concentrated energy source, storing more than double the energy per gram compared to carbohydrates and proteins.
- Insulation and Protection: Help maintain body temperature and protect vital organs.
- Cell Membrane Structure: Phospholipids form the bilayer of cell membranes.
- Absorption of Vitamins: Facilitate the absorption of fat-soluble vitamins (A, D, E, K).
- Saturated Fats: Animal fats, butter, and coconut oil.
- Unsaturated Fats: Vegetable oils, nuts, seeds, and fish.
- Trans Fats: Partially hydrogenated oils used in some processed foods.
Vitamins
Vitamins are organic compounds required in small quantities for various metabolic processes. They are categorized into water-soluble and fat-soluble vitamins.
Function:
Vitamins play diverse roles, including:
- Energy Production: B vitamins are essential for converting food into energy.
- Immune Function: Vitamins A, C, and E support the immune system.
- Bone Health: Vitamin D aids in calcium absorption.
- Antioxidant Activity: Vitamins C and E protect cells from damage.
- Vitamin A: Carrots, sweet potatoes, and spinach.
- Vitamin C: Citrus fruits, strawberries, and bell peppers.
- Vitamin D: Sunlight exposure, fortified dairy products, and fatty fish.
- B Vitamins: Whole grains, meat, eggs, and legumes.
- Vitamin E: Nuts, seeds, and vegetable oils.
Minerals
Minerals are inorganic elements that play critical roles in the body. They are classified into major minerals and trace minerals based on the quantities required.
Function:
Minerals are vital for:
- Bone Structure: Calcium and phosphorus form bones and teeth.
- Fluid Balance: Sodium and potassium maintain osmotic balance.
- Nerve Transmission: Sodium, potassium, and calcium facilitate nerve impulses.
- Enzyme Function: Zinc and magnesium act as cofactors for enzymatic reactions.
- Calcium: Dairy products, leafy green vegetables, and fortified foods.
- Iron: Red meat, beans, and fortified cereals.
- Magnesium: Nuts, whole grains, and green leafy vegetables.
- Zinc: Meat, shellfish, and legumes.
- Potassium: Bananas, oranges, and potatoes.
- Sodium: Table salt and processed foods.
Water
Water is a colorless, tasteless liquid essential for all known forms of life. It constitutes about 60% of the human body and is vital for various physiological processes.
Function:
Water is crucial for:
- Transportation: Acts as a solvent, carrying nutrients and waste products in the blood.
- Temperature Regulation: Helps maintain body temperature through sweating and respiration.
- Chemical Reactions: Participates in hydrolysis and other metabolic reactions.
- Lubrication: Cushions joints and protects sensitive tissues.
- Drinking Water: Plain water, mineral water, and infused water.
- Beverages: Juices, milk, and herbal teas.
- Food: Fruits and vegetables with high water content, such as cucumbers and watermelon.
Fiber
Dietary fiber refers to plant-based carbohydrates that are not digested by human enzymes. It is divided into soluble and insoluble fiber.
Function:
Fiber contributes to:
- Digestive Health: Promotes regular bowel movements and prevents constipation.
- Blood Sugar Control: Soluble fiber slows the absorption of sugar, aiding in glucose regulation.
- Lipid Levels: Helps reduce cholesterol levels by binding to bile acids.
- Satiety: Enhances feelings of fullness, aiding in weight management.
- Fruits and Vegetables: Apples, berries, carrots, and broccoli.
- Whole Grains: Oats, brown rice, and whole wheat products.
- Legumes: Beans, lentils, and peas.
- Nuts and Seeds: Almonds, chia seeds, and flaxseeds.
Advanced Concepts
Metabolism of Carbohydrates
Carbohydrate metabolism involves two primary pathways: glycolysis and the citric acid cycle.
Glycolysis:
Glycolysis is the anaerobic breakdown of glucose into pyruvate, producing a net gain of 2 ATP molecules and 2 NADH molecules per glucose molecule.
$$\text{Glucose} + 2 \text{NAD}^+ + 2 \text{ADP} + 2 \text{P}_\text{i} \rightarrow 2 \text{Pyruvate} + 2 \text{NADH} + 2 \text{ATP} + 2 \text{H}_2\text{O}$$
Citrate Acid Cycle:
Also known as the Krebs cycle, it occurs in the mitochondria, where acetyl-CoA derived from pyruvate is oxidized to produce NADH, FADH₂, and GTP (or ATP).
Oxidative Phosphorylation:
NADH and FADH₂ donate electrons to the electron transport chain, leading to the production of a substantial amount of ATP through chemiosmosis.
Interconnection with Other Metabolic Pathways:
Carbohydrate metabolism is interconnected with lipid and protein metabolism, allowing the body to adapt to different energy demands and nutrient availabilities.
Protein Synthesis and Degradation
Protein synthesis is a fundamental process involving transcription and translation.
Transcription:
Occurs in the nucleus where DNA is transcribed into messenger RNA (mRNA).
Translation:
mRNA is translated by ribosomes in the cytoplasm to form polypeptide chains, which fold into functional proteins.
Protein Degradation:
Proteins are broken down by proteolytic enzymes into amino acids, which can be reused for new protein synthesis or converted into other compounds.
Regulation of Protein Synthesis:
Controlled by various factors including hormonal signals, availability of amino acids, and feedback mechanisms ensuring cellular homeostasis.
Lipid Metabolism and Storage
Lipids undergo complex metabolic processes involving synthesis and breakdown.
Lipogenesis:
The process of synthesizing fatty acids and triglycerides from acetyl-CoA and glycerol, primarily occurring in adipose tissue and the liver.
Beta-Oxidation:
Fatty acids are broken down in the mitochondria to generate acetyl-CoA, which enters the citric acid cycle for energy production.
Ketogenesis:
In conditions of prolonged fasting or carbohydrate deficiency, acetyl-CoA is converted into ketone bodies, providing an alternative energy source for the brain and other tissues.
Interdisciplinary Connections:
Lipid metabolism is closely linked to endocrinology and cardiovascular physiology, influencing hormone synthesis and heart health.
Vitamins and Their Biochemical Roles
Vitamins act as coenzymes and cofactors in numerous biochemical reactions.
Vitamin B Complex:
Includes B1 (thiamine), B2 (riboflavin), B3 (niacin), B6, B12, and others, all of which play roles in energy metabolism by facilitating enzymatic reactions in glycolysis, the citric acid cycle, and oxidative phosphorylation.
Vitamin D and Calcium Homeostasis:
Vitamin D promotes the absorption of calcium from the gastrointestinal tract and maintains adequate serum calcium and phosphate levels for bone formation and remodeling.
Antioxidant Vitamins:
Vitamins C and E protect cells from oxidative damage by neutralizing free radicals, thus preventing cellular aging and reducing the risk of chronic diseases.
Interdisciplinary Connections:
Biochemistry and molecular biology intersect with nutrition in understanding how vitamins influence genetic expression and enzymatic functions.
Water Balance and Homeostasis
Maintaining water balance is critical for physiological homeostasis, involving mechanisms of intake, excretion, and distribution.
Regulation Mechanisms:
The kidneys play a pivotal role in water balance by adjusting the concentration of urine through the actions of antidiuretic hormone (ADH). When water intake is low, ADH levels increase, reducing urine output to conserve water.
Osmoregulation:
Maintains the balance of electrolytes and water across cell membranes, ensuring proper cell function and preventing dehydration or overhydration.
Interconnection with Other Systems:
Hydration status affects cardiovascular function, renal efficiency, and neurological activity, highlighting the integrative nature of bodily systems.
Dietary Fiber and Gut Health
Dietary fiber influences gut microbiota composition and gastrointestinal physiology.
Fermentation of Fiber:
Soluble fiber is fermented by gut bacteria into short-chain fatty acids (SCFAs), which serve as an energy source for colonocytes and have systemic anti-inflammatory effects.
Prebiotic Effects:
Fiber acts as a prebiotic, promoting the growth of beneficial bacteria in the gut, thereby enhancing immune function and protecting against pathogenic microorganisms.
Metabolic Implications:
High-fiber diets are associated with reduced risks of type 2 diabetes, cardiovascular disease, and certain cancers, illustrating the role of fiber in metabolic health.
Comparison Table
| Nutrient | Primary Function | Key Sources |
|---|---|---|
| Carbohydrates | Primary energy source | Grains, fruits, vegetables, sugars |
| Proteins | Structural components, enzymes, hormones | Meat, fish, eggs, legumes, nuts |
| Fats | Energy storage, insulation, cell membranes | Oils, butter, nuts, fish, avocados |
| Vitamins | Metabolic processes, immune function | Fruits, vegetables, dairy, meat, fortified foods |
| Minerals | Bone formation, fluid balance, enzyme function | Dairy, meat, grains, nuts, vegetables |
| Water | Hydration, temperature regulation, transport of nutrients | Water, beverages, high-water-content foods |
| Fiber | Digestive health, blood sugar control, cholesterol reduction | Whole grains, fruits, vegetables, legumes |
Summary and Key Takeaways
- Nutrients are vital for energy, growth, and bodily functions.
- Carbohydrates provide primary energy, with various sources from simple to complex.
- Proteins are essential for structure, enzymes, and hormonal functions.
- Fats serve as energy storage, insulation, and are crucial for cell membranes.
- Vitamins act as coenzymes and support immune and metabolic functions.
- Minerals are key for bone health, fluid balance, and enzymatic processes.
- Water maintains hydration, regulates temperature, and facilitates nutrient transport.
- Fiber promotes digestive health and aids in regulating blood sugar and cholesterol levels.
Coming Soon!
Examiner Tip
Tips
Use the mnemonic "CHOW MFP" to remember the main nutrients: Carbohydrates, Hydrocarbons (fats), Proteins, Minerals, Fiber, and Water. Additionally, create flashcards for each vitamin and mineral to reinforce their functions and sources, aiding in quick recall during exams.
Did You Know
Did You Know
Did you know that the human body can store only about 400 grams of carbohydrates, while it can store up to 100 kilograms of fat? This highlights the body's preference for storing energy as fat. Additionally, certain vitamins like Vitamin D can be synthesized by the body when exposed to sunlight, reducing the need to obtain them entirely from dietary sources.
Common Mistakes
Common Mistakes
Students often confuse monosaccharides and disaccharides. For example, mistaking glucose (a monosaccharide) for sucrose (a disaccharide) can lead to incorrect answers in exams. Another common error is underestimating the importance of fiber; students might neglect its role in digestive health, focusing solely on macronutrients.
FAQ
What are the primary functions of carbohydrates in the body?
Carbohydrates provide the main source of energy, especially for the brain and muscles, store energy as glycogen, and spare proteins from being used as an energy source.
How do proteins contribute to immune function?
Proteins form antibodies that help identify and neutralize pathogens, playing a critical role in the immune response.
What is the difference between saturated and unsaturated fats?
Saturated fats are typically solid at room temperature and found in animal products, while unsaturated fats are liquid and found in plant oils and fish.
Why is fiber important for digestive health?
Fiber adds bulk to the diet, promotes regular bowel movements, and supports a healthy gut microbiome, preventing constipation and other digestive issues.
How does water regulate body temperature?
Water helps maintain body temperature through sweating and respiration, dissipating excess heat and cooling the body.
What are the consequences of vitamin D deficiency?
Vitamin D deficiency can lead to weakened bones in children (rickets) and adults (osteoporosis), impairing bone health and calcium absorption.
1.
Plant Nutrition
2.
Gas Exchange in Humans
3.
Reproduction
4.
Human Nutrition
5.
Respiration
6.
Characteristics and Classification of Living Organisms
7.
Inheritance
8.
Excretion in Humans
9.
Transport in Plants
10.
Coordination and Response
11.
Organisation of the Organism
12.
Variation and Selection
13.
Movement into and out of Cells
14.
Transport in Animals
15.
Organisms and Their Environment
16.
Biological Molecules
17.
Drugs
18.
Human Influences on Ecosystems
19.
Diseases and Immunity
20.
Enzymes
21.
Biotechnology and Genetic Modification
Get PDF
How would you like to practise?
