Nutrition in Plants

• Nutrition involves taking in food and converting it to energy and vital nutrients.
• Nutrients are substances providing energy and biomolecules for body functions.
• All organisms need nutrients.
• Nutrient needs and modes of nutrition vary between species

Types of Nutrition

• Autotrophic and heterotrophic are the two types of nutrition among living organisms.

Autotrophic Nutrition

• In autotrophic nutrition, organisms use inorganic matter, light, and chlorophyll to synthesize their own food, like glucose via photosynthesis.
• Autotrophs include plants, algae, and cyanobacteria.

Heterotrophic Nutrition

• Heterotrophic organisms depend on others for nutrition.
• Fungi, animals, and humans are heterotrophs.
• Herbivores eat plants, carnivores eat animals, and omnivores eat both.
• Heterotroph survival relies directly or indirectly on plants.

Categories of Heterotrophs

• Parasites (leeches, ticks)
• Saprophytes (mushrooms)
• Holozoic (humans, dogs)
• Symbiotic (lichens)
• Insectivorous (Venus fly trap, pitcher plant, cobra lily)
• Holozoic nutrition involves ingestion, digestion, absorption, and assimilation of solid and liquid material
• Amoeba exhibit this type of nutrition
• Saprophytic nutrition involves organisms feeding on dead and decaying matter
• Bacteria and fungi utilize this mode of nutrition
• Parasitic nutrition involves organisms living on or in a host at the host's expense
• Lice and tapeworms use this mode of nutrition
• Symbiotic nutrition is when 2 organisms live together, sharing shelter and nutrients
• Algae and fungus in lichens follow this process
• Insectivorous plants consume insects, growing in humid, nitrogen-deficient soil- These are often called carnivorous plants

Plant Nutrition

• During photosynthesis, plants convert carbon dioxide and water into carbohydrates, which are stored as starch
• Plants derive energy from this starch
• Photosynthesis occurs in three basic stages: absorption, conversion, reduction

Photosynthesis Stages

• Absorption involves chlorophyll trapping light from the sun

• Conversion turns light energy into chemical energy and splits water into hydrogen and oxygen

• Reduction is the combining of hydrogen molecules with carbon dioxide to form carbohydrates (sugar molecules)

• Not all 3 photosynthetic events happen continuously or sequentially

• Stomata are openings on leaves that facilitate gas exchange, regulated via guard cells

• In deserts, guard cells close stomata during the day to prevent water loss and open at night to store carbon dioxide in vacuoles for daytime photosynthesis

• Plants need soil for micro and macro elements to synthesize proteins and other essential compounds

• Photosynthesis is a metabolic reaction where light energy converts raw materials into carbohydrates like glucose for energy via respiration

• Photosynthesis occurs in plant cell chloroplasts, which contain chlorophyll, that transfers light energy into chemical energy to make carbohydrates

Photosynthesis Equation

• Carbon dioxide + water yields glucose + oxygen.
• 6CO2 + 6H2O yields C6H12O6 + 6O2

Factors Affecting Photosynthesis

• The limiting factor determines the rate of photosynthesis.
• Light intensity: Low light limits photosynthesis, regardless of carbon dioxide or temperature.
• Carbon dioxide concentration: Increased CO2 raises photosynthesis rate.
• Temperature: Enzymes drive photosynthesis, so it has an optimum temperature, often about 25°C. Low temperatures slow it, and high temperatures denature enzymes, also slowing it.
• High light intensity can increase temperature.

Human Nutrition

• Humans require different nutrients, obtained through a balanced diet to provide essential nutrients in correct amounts for growth and repair
• Balanced diets vary based on age, gender, and physical activity, meaning pregnant and breastfeeding women need more nutrients to feed themselves and their babies

Nutrients and Their Importance

• Carbohydrates: Provide energy for respiration and are found in rice, pasta, and potatoes. Proteins: broken down into amino acids, that produce new proteins of protein synthesis
• Fats: Important for insulation, energy, waterproofing, structure, and protection; found in fatty meats, cheese, and butter.
• Vitamins C and D: Vitamin C aids in protein synthesis and tissue repair; found in citrus fruits; Vitamin D helps calcium uptake and maintains healthy bones
• Mineral salts like calcium and iron: Calcium is needed for bones, teeth, and blood clotting; found in dairy and fish. Iron aids in oxygen transport; found in red meat and green vegetables.
• Fibre (roughage): Found in vegetables, fruit, and grains. It aids digestion.
• Water: Acts as a solvent and helps regulate body temperature.

Malnutrition and its Outcomes

• Starvation: Eating too little food, leading to weight loss, organ damage, muscle atrophy, and death.
• Constipation: Lack of fibre, leading to pain and inability to defecate.
• Coronary heart disease: Cholesterol buildup limits blood flow, causing heart attacks.
• Cholesterol is from saturated fat in high-fat dairy and fatty meats.
• Obesity: Eating too much food, leading to diabetes, high blood pressure, strokes, and heart disease.
• Scurvy: Lack of vitamin C, leading to bleeding, stunted growth, and dry skin.
• Kwashiorkor and marasmus: Conditions due to protein-energy malnutrition, which involves either protein or calorie deficiency over time.

Examples Of Vitamin Deficiency Diseases

• Vitamin A deficiency causes night blindness.
• Vitamin B1 deficiency causes Beri-beri.
• Vitamin B2 causes Retarded growth and bad skin.
• Vitamin B12 deficiency causes Anaemia.
• Vitamin C deficiency causes Scurvy.
• Vitamin D deficiency causes Rickets.
• Vitamin K deficiency causes Excessive bleeding due to injury.

Examples Of Mineral Deficiency Diseases

• Calcium deficiency causes Brittle bones and excessive bleeding.
• Phosphorus deficiency causes Bad teeth and bones.
• Iron deficiency causes Anaemia.
• Iodine deficiency causes Goitre and enlarged thyroid gland.
• Copper deficiency causes Low appetite and retarded growth.

Alimentary Canal

• Food undergoes mechanical and chemical digestion after ingestion
• Mechanical digestion: physically breaking down food without changing its chemical nature
• Chemical digestion: breaking down large, insoluble molecules into smaller, soluble ones by enzymes for absorption
• Absorption: uptake of small molecules/ions through the gut wall into the blood
• Assimilation: molecules are transported to cells and utilized in metabolic processes
• Egestion: removal of undigested and unabsorbed waste as feces

Parts of the Alimentary Canal

• Mouth and salivary glands: Food is mechanically digested, and saliva starts chemical digestion of starch.

• Oesophagus: Passes food from the mouth to the stomach via peristalsis

• Stomach: Protease enzymes break down protein; hydrochloric acid creates a low pH to kills bacteria and facilitates enzyme activity

• Small intestine: Duodenum neutralizes stomach acidity for enzyme action. Protease, lipase, and amylase break down molecules, while the ileum absorbs digestion products into the blood

• Pancreas: It secretes juices containing lipase, protease, and amylase into the small intestine

• Liver: Produces bile which emulsifies fats and neutralizes stomach acid in the small intestine

• Gall bladder: Stores bile before release into the small intestine

• Large intestine: remaining salts and water are absorbed

Cholera

• Cholera is a disease caused by bacteria in contaminated food and water
• Bacteria stick to intestinal walls, releasing toxic proteins that cause chloride ion secretion, drawing water into the gut via osmosis, leading to diarrhoea
• Oral rehydration therapy can treat this by administering a water, glucose, and salts mixtures to counteract the water loss

Mechanical Digestion

• Incisors and canines tear food.
• Premolars and molars grind food.

Tooth Structure

• Enamel: Hard outer layer,
• Dentine: Underneath the enamel, more prone to decay.
• Pulp: Contains vessels and nerves.
• Cement: Stabilizes the root.

Tooth Decay

• Bacteria produce acids that dissolve enamel and dentine
• Brush regularly and reduce sugar intake

Chemical Digestion

• Important process to break down food for absorption.
• Amylase breaks down starch into maltose then into glucose
• Maltase is a membrane-bound enzyme in the small intestine
• Proteases (pepsin in stomach, trypsin in small intestine) break down proteins into amino acids.
• Lipase breaks down fats into glycerol and fatty acids.

Absorption

• Digestion in the small intestine for nutrient uptake
• Villi and microvilli increase surface area
• Capillaries carry absorbed molecules for a high concentration gradient
• Water is absorbed in the small intestine and colon.
• Lacteals absorb fats.