Functions of Life: Nutrition and Respiration

Functions of Life (Nutrition and Respiration)

• Plants produce food through photosynthesis, and also respire, releasing CO2. Animals obtain energy through digestion.
• Photosynthesis uses light energy to convert carbon dioxide and water into glucose and oxygen.
• Photosynthesis occurs in chloroplasts, containing chlorophyll.
• The formula for photosynthesis is 6CO2 + 6H2O → C6H12O6 + 6O2.

Internal and External Adaptations of Leaves

• Large leaf surface area maximizes light absorption for photosynthesis, especially in locations with abundant sunlight.
• Thin leaves minimize the diffusion distance for CO2 and O2.
• Veins transport water to all leaf parts and carry away glucose.
• Stomata allow gas exchange (CO2 in, O2 out).
• Transparent, waxy cuticles protect leaves from excessive water loss and prevent damage.
• Epidermis, one cell thick, allows sunlight to penetrate. Guard cells regulate stomata opening and closing.
• Palisade layer, rich in chloroplasts, is situated to effectively absorb sunlight.

Diagrammatic Representation of a Leaf Cross-Section

• The diagram illustrates the leaf's anatomy.
• Key structures include the upper epidermis, cuticle, palisade mesophyll, spongy mesophyll, lower epidermis, stomata, guard cells, xylem, and phloem.
• Spongy mesophyll contains air spaces for gas exchange and provides structural support.

Factors Affecting Photosynthesis

• Abiotic factors, like light intensity, CO2 levels, and temperature, influence photosynthesis.
• Light intensity affects photosynthesis rates; excessive light can damage leaves.
• Higher CO2 levels typically increase photosynthetic rates.
• Optimal temperatures promote enzyme activity for photosynthesis.

Oxygen Production Experiment

• Materials: aquatic plant, test tube, water, Sodium hydrogen carbonate, funnel, and splint.
• Method: Place plant in water with sodium hydrogen carbonate. Cover the plant with an inverted tube containing water.
• Results: Oxygen production (tested with a glowing splint) indicates successful photosynthesis.

Holozoic Nutrition

• Ingestion, digestion, absorption, assimilation, and egestion are the stages involved in holozoic nutrition.
• The alimentary canal, from mouth to anus, is the pathway for digestion
• Glands and hormones facilitate digestion and nutrient processing.
• Villi and microvilli increase the small intestine's surface area for efficient nutrient absorption.

Physical/Chemical Digestion

• Mechanical breakdown of food (chewing).
• Chemical breakdown involves enzymes altering food molecules for absorption.
• Digestion proceeds in the digestive tract; both mechanical and chemical processes involved.
• Digestive enzymes like amylase, pepsin, and bile have specific roles in digestion.

Enzymes

• Enzymes speed up chemical reactions.
• They are proteins, and don't get consumed in the reaction.
• Enzymes act on substrates, forming a complex.
• Enzyme activity is influenced by temperature, pH, and substrate concentration.
• Poisons can inhibit enzyme function through blocking active sites.

Cellular Respiration

• Cellular respiration involves combining oxygen and food molecules to produce ATP (energy).
• CO2 and water are released as waste products.
• ATP acts as the primary energy currency for cells.
• Aerobic respiration requires oxygen, and anaerobic does not.
• Anaerobic respiration produces comparatively fewer ATPs (2 vs. 36-38).

Alcoholic and Lactic Acid Fermentation

• Both processes are anerobic respiration pathways.
• Alcoholic fermentation produces ethanol and CO2 (yeast).
• Lactic acid fermentation produces lactic acid (animals).