Biology Paper Review: May-June 2023

Examination Guidelines

• Read instructions carefully.
• Clarify any questions with the examiner before starting.

Section A: Questions

Question 1: Micrographs of Animal and Plant Cells

• Type of Microscope Used: Electron microscope (provides detailed images of cell structures like nucleus, chloroplasts, etc.).
• Diagram Drawing: Ensure diagrams are large and clearly labeled (e.g., cell wall, nucleus, chloroplast).
• Similarities Between Plant and Animal Cells:
  • Cell membrane
  • Ribosomes
  • Vacuole
  • Cytoplasm
  • Nucleus
  • Mitochondria
• Prominent Structure in Animal Cell: Nucleus carries genetic information (DNA).

Question 2: Bacterial Cell Structure

• Similarity with Plant Cells: Both have a cell wall.
• Bacterial Cell Structures:
  • Flagellum: Movement towards target cells.
  • Capsule: Protection and adhesion.
  • Cell Wall: Protection against antibodies and phagocytes.

Question 3: Multicellular Organisms

• Cell Types:
  • Red Blood Cells: No nucleus, biconcave, contains hemoglobin.
  • Skin Cells: Have a nucleus.
  • Nerve Cells: Have axons and dendrites, myelin sheath.
• Identifying Bacterial Cells: Lack of nucleus, circular DNA, plasmids, cell wall, capsule, flagella.

Section B: Meiosis

Meiosis Process

• Chromosome Arrangement: Crossing over and independent assortment lead to genetic diversity.
• Daughter Cells: Haploid (half the number of chromosomes).
• Location of Meiosis: Ovaries or testicles.
• Genetic Structure: Chromosomes contain genetic material (DNA).

Genetic Variation

• Causes:
  • Crossing over during prophase I.
  • Recessive alleles leading to different phenotypes.

Importance of Meiosis

• Genetic Variation: Increases survival and adaptation.
• Reduction of Genetic Disorders: E.g., sickle cell reduction.
• Gamete Production: For sexual reproduction.
• Chromosome Maintenance: Ensures diploid number upon fertilization.

Section C: Classification and Conservation

Organism Classification

• Kingdoms:
  • Plantae
  • Bacteria (Monera)
  • Fungi
  • Protista
• Fish Classification: Based on mouth shape, body shape, fin size, body patterns.

Conservation Methods

• Pollution Control: Proper waste disposal and sewage treatment.
• Regulation: Open and closed seasons, prohibition of releasing pets into wild.
• Invasive Species Control: Manage non-native species.

Section D: Cellular and Transport Processes

Unicellular vs. Multicellular

• Unicellular Examples: Bacteria, protists (Amoeba, Euglena), yeast.
• Materials Transported in Multicellular Organisms:
  • Water
  • Glucose
  • Amino acids
  • Hormones

Transport System Necessity

• Size and Complexity: Multicellular organisms require transport systems for substance delivery across large distances.

Section E: Plant Processes

Definitions

• Translocation: Transport of sucrose via phloem.
• Transpiration: Evaporation of water from plant surfaces (leaves).

Xylem and Phloem Functionality

• Xylem: Dead tissue allows easy water transport, aids capillary action.
• Phloem: Active transport facilitates nutrient delivery.

Section F: Respiration and Gas Exchange

Definitions

• Diffusion: Movement from high to low concentration.
• Breathing: Inhalation and exhalation of air.
• Respiration: Energy production from glucose.

Muscle Function in Breathing

• Muscles: Diaphragm, intercostal muscles (internal and external).

Gas Exchange

• Process: Oxygen and carbon dioxide diffusion across alveoli and capillaries.
• Alveoli Properties: Thin, moist, large surface area.

Anaerobic Respiration

• During Exercise: Oxygen debt leads to lactic acid production for quick energy.

Section G: Excretion and Homeostasis

Definitions

• Egestion: Removal of undigested food.
• Excretion: Removal of metabolic waste.

Excretory Organs

• Examples:
  • Lungs: Excrete carbon dioxide.
  • Kidneys: Excrete urea and excess water.

Kidney Function in Fluid Balance

• Response to Dehydration: ADH secretion increases water reabsorption, reduces urine volume.

Plant Water Conservation

• Methods:
  • Closing stomata
  • Thick waxy cuticles
  • Small or narrow leaves
  • Leaf shedding

---

These notes summarize key points from the biology paper review for May-June 2023, providing a comprehensive study guide.