Life science summary

Diversity in Life Sciences

Energy and Oxygen Production

  • Photosynthesis:

    • Process that converts light energy to chemical energy stored in glucose.

    • Inputs: Carbon Dioxide (CO₂), Water (H₂O), and Sunlight.

    • Outputs: Glucose (C₆H₁₂O₆) and Oxygen (O₂).

  • Cellular Respiration:

    • The process of converting glucose into energy in the form of ATP.

    • Involves both aerobic (with oxygen) and anaerobic (without oxygen) processes.

Cell Structure Knowledge (Revision from Grade 10)

Biological Terms

  • Carbohydrate: Organic compounds including glucose and starch.

  • Chloroplast: Plastid containing chlorophyll; site of photosynthesis in plant cells.

  • Epidermal Cells: Transparent cells in the leaf surface; do not contain chloroplasts.

  • Guard Cells: Cells that regulate stomata opening for gas exchange.

  • Stoma: Opening for gas diffusion in leaves.

Plant Cell Components

  • Chloroplasts: Site of photosynthesis.

  • Mitochondria: Produce ATP through cellular respiration.

  • Vacuole: Storage area for nutrients and waste products.

  • Xylem and Phloem: Conduct water and nutrients throughout the plant.

Photosynthesis - Processes and Importance

Processes of Photosynthesis

  • Light Phase: Occurs in grana of chloroplasts.

    • Requires sunlight; water splits (photolysis) to release O₂ and produce ATP.

  • Dark Phase (Calvin Cycle): Occurs in stroma of chloroplasts.

    • No light required; uses CO₂ and ATP to produce glucose.

  • Importance of Photosynthesis:

    • Provides energy for nearly all organisms.

    • Contributes to the carbon cycle and oxygen supply for respiration.

    • Plants convert simple sugars into complex macromolecules.

Human Nutrition and Digestive System

Anatomy of the Digestive System

  • Alimentary Canal: Mouth, pharynx, oesophagus, stomach, small intestine, large intestine.

  • Accessory Organs: Tongue, teeth, salivary glands, pancreas, liver, gall bladder.

Steps in Digestion

  • Ingestion: Taking food into the mouth.

  • Digestion: Mechanical and chemical breakdown of food.

  • Absorption: Nutrients absorbed in the small intestine, mainly via villi.

  • Egestion: Elimination of waste (feces) from the body.

Nutrient Absorption

  • Glucose, amino acids absorbed actively.

  • Fats absorbed through lacteals of villi.

  • Importance of fiber for digestion: promotes movement and prevents constipation.

Homeostasis in Human Nutrition

Hormonal Control of Blood Sugar Levels

  • Insulin: Lowers blood glucose by converting glucose to glycogen (stored form).

  • Glucagon: Raises blood glucose by converting glycogen back to glucose.

  • Negative Feedback Mechanism: Maintains stability in blood glucose levels by opposing deviations.

Cellular Respiration

Aerobic and Anaerobic Processes

  • Aerobic Respiration: Utilizes oxygen; produces high amounts of ATP, CO₂ and H₂O as by-products.

  • Anaerobic Respiration: Occurs without oxygen; produces less ATP. In animals, it results in lactic acid, whereas in plants it results in ethanol.

Comparison of Respiration

Factor

Aerobic Respiration

Anaerobic Respiration

Oxygen Required

Yes

No

By-products

CO₂ and H₂O

Lactic Acid / Ethanol

ATP Yield

High

Low

Scientific Investigations

  • Hypothesis formulation, experimentation and result analysis essential for understanding processes such as cellular respiration and photosynthesis.