Biology Notes on Plant Nutrition & Human Nutrition PDF

BIOLOGY NOTES Chapter 6: Plant Nutrition 6.1 Photosynthesis Photosynthesis is the process by which plants synthesize carbohydrates from raw materials using energy from light. Word Equation for Photosynthesis: Carbon dioxide+Water→Glucose+Oxygen\text{Carbon dioxide} + \text{Water} \rightarrow \te...

BIOLOGY NOTES Chapter 6: Plant Nutrition 6.1 Photosynthesis Photosynthesis is the process by which plants synthesize carbohydrates from raw materials using energy from light. Word Equation for Photosynthesis: Carbon dioxide+Water→Glucose+Oxygen\text{Carbon dioxide} + \text{Water} \rightarrow \text{Glucose} + \text{Oxygen} (In the presence of light and chlorophyll) Balanced Chemical Equation: 6CO2+6H2O→C6H12O6+6O26CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2 Role of Chlorophyll: A green pigment found in chloroplasts Transfers energy from light into chemical energy for the synthesis of carbohydrates Uses and Storage of Carbohydrates in Plants: Starch: Stored as an energy reserve Cellulose: Used to build cell walls Glucose: Used in respiration to provide energy Sucrose: Transported in the phloem Nectar: Attracts insects for pollination Essential Mineral Ions for Plants: Nitrate Ions: Needed for making amino acids, proteins, and enzymes Magnesium Ions: Required for making chlorophyll Factors Affecting Photosynthesis:  Light intensity: More light increases the rate up to a point Carbon dioxide concentration: Higher CO₂ levels increase photosynthesis rate Temperature: Enzymes involved in photosynthesis work best at optimal temperatures Investigations in Photosynthesis: Testing for starch: Iodine solution turns blue-black if starch is present Need for chlorophyll: Variegated leaves show starch only in green areas Effect of light and dark conditions: Hydrogencarbonate indicator detects CO₂ changes Leaf Structure and Adaptations for Photosynthesis: Large Surface Area: Maximizes light absorption Thin Structure: Reduces diffusion distance for gases Stomata and Guard Cells: Regulate gas exchange Palisade Mesophyll: Contains many chloroplasts for efficient light absorption Spongy Mesophyll: Facilitates gas diffusion with air spaces Xylem and Phloem: Transport water, minerals, and products of photosynthesis Chapter 7: Human Nutrition 7.1 Diet and Nutrients A balanced diet includes the correct proportions of essential nutrients: Carbohydrates: Energy source (e.g., bread, rice, potatoes) Proteins: Growth and repair (e.g., meat, fish, beans) Fats and Oils: Energy storage, insulation (e.g., butter, nuts, avocados) Vitamins: o Vitamin C: Prevents scurvy (found in citrus fruits) o Vitamin D: Prevents rickets, needed for calcium absorption (found in dairy, sunlight) Minerals: o Calcium: Strong bones and teeth (found in milk, green vegetables) o Iron: Required for hemoglobin in red blood cells (found in red meat, spinach) Fibre (Roughage): Aids digestion by preventing constipation (found in whole grains, vegetables)  Water: Essential for chemical reactions and maintaining homeostasis 7.2 Digestive System and Functions: Mouth: Ingestion, mechanical digestion by teeth, chemical digestion by amylase Oesophagus: Moves food to stomach via peristalsis Stomach: Produces hydrochloric acid to kill microbes, secretes protease enzymes Small Intestine: Completes digestion, absorbs nutrients into blood Large Intestine: Absorbs water, forms faeces Liver: Produces bile to emulsify fats Pancreas: Secretes digestive enzymes (amylase, protease, lipase) 7.3 Physical and Chemical Digestion Physical Digestion: Breaking food into smaller pieces without chemical change (e.g., chewing, stomach churning) Chemical Digestion: Breakdown of large molecules into smaller molecules by enzymes: o Amylase: Starch → Maltose o Protease (Pepsin/Trypsin): Proteins → Amino acids o Lipase: Fats → Fatty acids + Glycerol Bile: Neutralizes stomach acid and emulsifies fats 7.4 Absorption of Nutrients in the Small Intestine: Villi and Microvilli: Increase surface area for absorption Capillaries: Absorb glucose and amino acids into the bloodstream Lacteals: Absorb fatty acids and glycerol into the lymphatic system Water Absorption: Most occurs in the small intestine, some in the colon