Essential Biology Concepts and Classification Principles
Biological Classification and Systems
1. Five-Kingdom Classification
Who proposed the five-kingdom system of classification?
Ans: The five-kingdom system of classification was proposed by R.H. Whittaker in 1969.
2. Kingdom Protista
Which kingdom shows a link with all eukaryotic members?
Ans: Kingdom Protista serves as a link with other eukaryotic kingdoms like Plantae, Fungi, and Animalia.
3. Commercial Use of Red Algae
What is the commercial use of red algae?
Ans: Red algae (such as Gelidium and Gracilaria) are used to produce Agar, which is used in the preparation of ice creams, jellies, and as a culture medium in laboratories.
4. Body Plans in Phyla
Which phylum onwards do all phyla show a tube-within-a-tube body plan?
Ans: The tube-within-a-tube body plan starts from Phylum Aschelminthes (Roundworms) and continues in all higher phyla.
5. Reptilian Heart Structure
Which animal shows a near four-chambered condition in reptiles?
Ans: Crocodiles are the reptiles that possess a complete four-chambered heart.
Cell Biology and Genetics
6. Polymorphic Organelles
Name the polymorphic organelle in the cell.
Ans: Lysosomes are considered polymorphic organelles because they exist in different forms (primary, secondary, residual bodies) based on their function.
7. Histone Synthesis
Synthesis of histones takes place in which phase of interphase?
Ans: The synthesis of histone proteins occurs during the S-phase (Synthetic phase) of the cell cycle.
8. Genetic Recombination
Which event during prophase-I results in genetic recombination?
Ans: The process of crossing over (which occurs during the Pachytene stage) results in genetic recombination.
Plant and Human Physiology
9. Angiospermic Plant Structure
Enlist the morphological structures observed in a typical angiospermic plant.
Ans: A typical angiospermic plant consists of two main systems:
- Root System: Primary and secondary roots.
- Shoot System: Stem, leaves, flowers, fruits, and seeds.
10. Hormonal Regulation
Which hormone-like substances are produced by the kidney?
Ans: The kidneys produce Erythropoietin (which stimulates RBC production), Calcitriol, and Renin.
Name the hormones secreted by the pancreatic Islets of Langerhans.
Ans: The main hormones are Insulin (secreted by β-cells) and Glucagon (secreted by α-cells).
11. Marasmus and Malnutrition
What is Marasmus? What are the symptoms?
Marasmus is a severe form of Protein-Energy Malnutrition (PEM) primarily affecting infants under one year of age. It is caused by a simultaneous deficiency of both proteins and calories.
Symptoms: Extreme emaciation (thinness), prominent ribs, wrinkled skin, and completely arrested growth.
12. Urine Formation Process
Urine formation involves three main steps:
- Ultrafiltration: Blood is filtered under high pressure in the Glomerulus into the Bowman’s capsule.
- Selective Reabsorption: Essential substances like glucose, amino acids, and water are reabsorbed back into the blood from the renal tubules.
- Tubular Secretion: Harmful wastes and ions (like H⁺ and K⁺) are actively secreted into the tubule to be excreted.
Enzymes, Tissues, and Botany
13. Induced Fit Model
Proposed by Daniel Koshland, this model suggests:
- The active site of an enzyme is not rigid.
- When a substrate approaches, the enzyme undergoes a conformational change to fit the substrate perfectly.
- After the reaction, the enzyme returns to its original shape.
14. Secondary Metabolites
While they are “waste” for plants, they are highly useful for humans:
- Medicines: Alkaloids like Morphine (painkiller) and Quinine (anti-malarial).
- Industry: Rubber, Gums, and Resins.
- Scents/Flavors: Essential oils used in perfumes and spices.
15. Earthworms and Vermicompost
Role of Earthworms: They are “Friends of Farmers” because they burrow into the soil, improving aeration and drainage while turning the soil to increase fertility.
Vermicompost: It is high-quality organic manure produced by the decomposition of organic waste (like kitchen waste) using earthworms.
16. Tissue Identification
- Inner lining of intestine: Simple Columnar Epithelium.
- Heart wall: Cardiac Muscle Tissue.
- Inner lining of buccal cavity: Non-keratinized Stratified Squamous Epithelium.
17. Binomial Nomenclature
It is a formal system of naming species with two parts: Genus and Species.
Rules:
- The Genus name starts with a Capital letter, and the Species name starts with a small letter.
- When handwritten, both names must be underlined separately.
- When printed, they must be in Italics.
18. Muscle Properties
- Excitability: Ability to respond to an electrical stimulus.
- Contractility: The muscle shortens or generates tension when stimulated.
- Extensibility: The ability to be stretched.
- Elasticity: The ability to return to original shape after contraction or stretching.
19. Areolar Connective Tissue
It is a loose connective tissue found beneath the skin and surrounding organs.
Components: It consists of a semi-fluid matrix containing Fibroblasts, Macrophages, and Mast cells, along with a network of Collagen (white) and Elastin (yellow) fibers.
20. Leaf Structure and Placentation
A leaf is a lateral, flattened green structure borne on the stem specialized for photosynthesis.
Parts: Leaf Base, Petiole, and Lamina (Leaf Blade).
Placentation Types: Marginal, Axile, Parietal, Free Central, and Basal.