Biology Basics

Understanding fundamental biology concepts is essential for RRB exam preparation. This section covers human biology, plant biology, and environmental science.

Cell Biology

Cell Structure and Function

Basic Cell Components

• Cell Membrane: Outer boundary, controls entry and exit of substances
• Cytoplasm: Jelly-like substance containing organelles
• Nucleus: Control center containing genetic material
• Mitochondria: Powerhouse of the cell, produces energy

Cell Organelles

• Endoplasmic Reticulum: Protein synthesis and transport
• Golgi Apparatus: Processing and packaging of proteins
• Lysosomes: Digestive enzymes, waste removal
• Ribosomes: Protein synthesis sites

Cell Division

• Mitosis: Division for growth and repair
• Meiosis: Division for reproduction
• Chromosomes: Genetic material carriers

Human Biology

Digestive System

Components

• Mouth: Mechanical and chemical digestion begins
• Esophagus: Food passage to stomach
• Stomach: Protein digestion, acid production
• Small Intestine: Nutrient absorption
• Large Intestine: Water absorption, waste formation

Digestive Enzymes

• Amylase: Carbohydrate digestion
• Protease: Protein digestion
• Lipase: Fat digestion
• Pepsin: Stomach protein digestion

Respiratory System

Respiratory Organs

• Nasal Cavity: Air filtration, warming, humidification
• Pharynx: Common passage for air and food
• Larynx: Voice box, air passage
• Trachea: Windpipe, air conduction
• Bronchi: Air passage to lungs
• Lungs: Gas exchange organs

Breathing Process

• Inspiration: Inhalation, diaphragm contraction
• Expiration: Exhalation, diaphragm relaxation
• Gas Exchange: Oxygen in, carbon dioxide out

Circulatory System

Heart Structure

• Four Chambers: Two atria, two ventricles
• Blood Vessels: Arteries, veins, capillaries
• Valves: Prevent backflow of blood

Blood Components

• Red Blood Cells: Oxygen transport, hemoglobin
• White Blood Cells: Immunity, disease fighting
• Platelets: Blood clotting
• Plasma: Liquid component, nutrients transport

Nervous System

Brain Parts

• Cerebrum: Higher brain functions, thinking
• Cerebellum: Balance, coordination
• Medulla: Vital functions, breathing, heart rate

Neuron Structure

• Cell Body: Nucleus and organelles
• Dendrites: Receive signals
• Axon: Transmit signals
• Synapse: Junction between neurons

Excretory System

Kidney Functions

• Filtration: Waste removal from blood
• Reabsorption: Useful substances reabsorbed
• Secretion: Additional waste removal
• Urine Formation: Waste excretion

Other Excretory Organs

• Skin: Sweat glands, temperature regulation
• Lungs: Carbon dioxide excretion
• Liver: Detoxification, waste processing

Reproductive System

Male Reproductive System

• Testes: Sperm production, testosterone
• Vas Deferens: Sperm transport
• Prostate Gland: Seminal fluid production
• Urethra: Urine and semen passage

Female Reproductive System

• Ovaries: Egg production, hormones
• Fallopian Tubes: Fertilization site
• Uterus: Fetal development
• Vagina: Birth canal

Plant Biology

Photosynthesis

Process Overview

• Light Reaction: Light energy capture
• Dark Reaction: Carbon dioxide fixation
• Chlorophyll: Green pigment, light absorption
• Stomata: Gas exchange pores

Chemical Equation

6CO� + 6H�O + Light Energy � C�H��O� + 6O�

Plant Tissues

Meristematic Tissues

• Apical Meristem: Growth at tips
• Intercalary Meristem: Growth at internodes
• Lateral Meristem: Growth in thickness

Permanent Tissues

• Parenchyma: Storage, photosynthesis
• Collenchyma: Support, flexible
• Sclerenchyma: Support, rigid
• Xylem: Water transport
• Phloem: Food transport

Plant Nutrition

Essential Nutrients

• Macronutrients: N, P, K, Ca, Mg, S
• Micronutrients: Fe, Mn, Zn, Cu, B, Mo, Cl
• Nitrogen Cycle: Atmospheric to plant-available

Water and Mineral Absorption

• Root Hairs: Increased surface area
• Active Transport: Energy-dependent uptake
• Transpiration Pull: Water movement upward

Microorganisms

Bacteria

Classification

• Shape: Cocci (spherical), Bacilli (rod), Spirilla (spiral)
• Gram Stain: Gram-positive, Gram-negative
• Oxygen Requirement: Aerobic, Anaerobic

Useful Bacteria

• Nitrogen Fixation: Rhizobium in legumes
• Food Production: Yogurt, cheese, pickles
• Decomposition: Organic matter breakdown

Harmful Bacteria

• Pathogenic Bacteria: Disease-causing
• Food Spoilage: Contamination and decay
• Infections: Various illnesses

Viruses

Characteristics

• Non-living: Require host cells
• Obligate Parasites: Cannot reproduce independently
• Simple Structure: Genetic material + protein coat

Virus Types

• DNA Viruses: Herpes, pox viruses
• RNA Viruses: Influenza, HIV, coronavirus
• Bacteriophages: Infect bacteria

Fungi

Fungal Characteristics

• Eukaryotic: True nucleus
• Heterotrophic: Cannot produce own food
• Cell Wall: Chitin composition

Useful Fungi

• Food: Mushrooms, yeast for bread
• Medicine: Antibiotics (penicillin)
• Decomposition: Organic matter recycling

Environmental Science

Ecosystem and Food Chains

Ecosystem Components

• Producers: Plants, photosynthetic organisms
• Consumers: Herbivores, carnivores, omnivores
• Decomposers: Bacteria, fungi
• Abiotic Factors: Light, water, temperature, soil

Food Chain Types

• Grazing Food Chain: Plant-based
• Detritus Food Chain: Dead organic matter
• Food Web: Interconnected food chains

Environmental Pollution

Air Pollution

• Sources: Vehicles, industries, burning
• Pollutants: CO, CO�, SO�, NO�, particulates
• Effects: Respiratory diseases, acid rain

Water Pollution

• Sources: Industrial waste, sewage, agriculture
• Pollutants: Heavy metals, pesticides, organic waste
• Effects: Waterborne diseases, ecosystem damage

Soil Pollution

• Sources: Pesticides, fertilizers, industrial waste
• Effects: Reduced fertility, crop contamination

Conservation of Natural Resources

Renewable Resources

• Solar Energy: Sustainable power source
• Wind Energy: Clean energy generation
• Biomass: Organic fuel sources
• Water: Cycle and conservation

Non-renewable Resources

• Fossil Fuels: Coal, petroleum, natural gas
• Minerals: Metals, non-metals
• Conservation: Efficient use, recycling

Conservation Methods

• Reduce: Minimize consumption
• Reuse: Multiple use of items
• Recycle: Material recovery and processing
• Afforestation: Tree planting

Important Biological Processes

Metabolism

• Anabolism: Building up processes
• Catabolism: Breaking down processes
• Energy Production: ATP generation

Homeostasis

• Temperature Regulation: Sweating, shivering
• Blood Sugar Regulation: Insulin, glucagon
• Water Balance: ADH hormone, kidney function

Genetics and Evolution

• DNA Structure: Double helix, nucleotides
• Protein Synthesis: Transcription, translation
• Natural Selection: Survival of the fittest
• Adaptation: Environmental adjustments

Practice Questions

Question 1

What is the powerhouse of the cell?

Question 2

Name the four chambers of the human heart.

Question 3

What is the chemical equation for photosynthesis?

Question 4

Which organelle is responsible for protein synthesis?

Question 5

What are the three types of blood vessels?

Question 6

Name the parts of the human digestive system in order.

Question 7

What is the function of hemoglobin in red blood cells?

Question 8

What are the main components of the nervous system?

Question 9

What is the difference between mitosis and meiosis?

Question 10

Name three types of plant tissues.

Question 11

What is the role of chlorophyll in photosynthesis?

Question 12

How do bacteria help in nitrogen fixation?

Question 13

What are the characteristics of viruses?

Question 14

What is the difference between aerobic and anaerobic respiration?

Question 15

Name the major greenhouse gases and their sources.

Quick Facts

Cell Biology Facts

• Human Cells: Approximately 37 trillion cells
• Cell Size: Varies from 1-100 micrometers
• Cell Division: 50-70 billion cells die daily
• DNA Length: 2 meters per cell, coiled

Human Body Facts

• Heart Rate: 60-100 beats per minute
• Breathing Rate: 12-20 breaths per minute
• Body Temperature: 37�C (98.6�F)
• Blood Volume: 4-5 liters in adults

Plant Biology Facts

• Photosynthesis Efficiency: 1-2% solar energy conversion
• Tree Age: Some live over 4,000 years
• Plant Species: Over 300,000 known species
• Oxygen Production: One tree produces oxygen for 2 people

Environmental Facts

• Oxygen Level: 21% of Earth’s atmosphere
• Biodiversity: 8.7 million species on Earth
• Forest Cover: 31% of Earth’s land surface
• Water Fresh: Only 3% of Earth’s water

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