Haryana Complete Biology - Class 10 Haryana Board Biology

Class 10 Biology: Core Concepts and Exam Questions

Life Processes: Nutrition and Respiration

Life processes include essential functions such as nutrition, respiration, transport, and excretion. Organisms obtain energy and materials for growth and maintenance through these processes. Two main modes of nutrition are described: autotrophic and heterotrophic.

• Autotrophic Nutrition: Organisms synthesize their own food from inorganic substances (CO$_2$, water) in the presence of sunlight and chlorophyll. Green plants and some bacteria use photosynthesis.
• Heterotrophic Nutrition: Organisms depend on other sources for food, unable to synthesize it themselves. Includes animals and fungi.
• Photosynthesis Requirements: CO$_2$, water,…

Class 10 Biology: Core Concepts and Exam Questions

Life Processes: Nutrition and Respiration

Life processes include essential functions such as nutrition, respiration, transport, and excretion. Organisms obtain energy and materials for growth and maintenance through these processes. Two main modes of nutrition are described: autotrophic and heterotrophic.

• Autotrophic Nutrition: Organisms synthesize their own food from inorganic substances (CO$_2$, water) in the presence of sunlight and chlorophyll. Green plants and some bacteria use photosynthesis.
• Heterotrophic Nutrition: Organisms depend on other sources for food, unable to synthesize it themselves. Includes animals and fungi.
• Photosynthesis Requirements: CO$_2$, water, sunlight, chlorophyll.
• Photosynthesis Products: Glucose, oxygen, water.
• Heterotrophic Strategies:
  • Holozoic: Ingestion and digestion inside the body (e.g., animals).
  • Saprophytic: Feeding on dead/decaying matter (e.g., fungi).
  • Parasitic: Living on/in another organism and deriving nutrition (e.g., tapeworm, lice).
• Energy for Life Processes: Obtained as ATP, mainly in mitochondria, but the reason for energy requirement is not solely explained by ATP production.

Human Digestive System and Digestion

The human digestive system consists of several organs that work together to break down food and absorb nutrients. Digestion begins in the mouth and continues through the alimentary canal.

• Main Parts: Mouth, tongue, esophagus, stomach, liver, pancreas, gall bladder, large intestine, small intestine, anus.
• Role of Saliva: Secreted by salivary glands under the tongue, contains salivary amylase enzyme which breaks down starch into simple sugars. Also softens food for easier swallowing.
• Role of Stomach Acid (HCl): Provides acidic pH for pepsin enzyme to digest proteins; kills germs in food.
• Longest Part of Alimentary Canal: Small intestine (6–7 meters in adults).
• Absorption in Small Intestine: Presence of villi increases surface area; blood vessels absorb digested food and transport it throughout the body.

Respiration: Aerobic and Anaerobic

Respiration is the process of breaking down glucose to release energy. It occurs in two main forms: aerobic and anaerobic.

• Aerobic Respiration: Requires oxygen, occurs in cytoplasm and mitochondria, complete breakdown of glucose, produces CO$_2$, water, and large energy.
• Anaerobic Respiration: Does not require oxygen, occurs in cytoplasm, incomplete breakdown of glucose, produces less energy, end products can be CO$_2$, ethanol (alcoholic fermentation), or lactic acid (lactic acid fermentation).
• Glucose Breakdown Pathways:
  • Glycolysis: Glucose (6C) breaks into pyruvate (3C).
  • In absence of oxygen: Pyruvate → ethanol + CO$_2$ + energy (yeast/alcoholic fermentation); Pyruvate → lactic acid + energy (muscle/lactic acid fermentation).
  • In presence of oxygen: Pyruvate → CO$_2$ + water + energy (aerobic respiration).

Transport and Circulation in Humans

Transport involves movement of substances like nutrients, gases, and wastes. The human circulatory system includes the heart, blood vessels, and blood.

• Heart Chambers: Right atrium, right ventricle, left atrium, left ventricle.
• Blood Flow:
  • Oxygenated blood from lungs enters left atrium.
  • Left atrium contracts, blood moves to left ventricle.
  • Left ventricle contracts, blood pumped to body via arteries.
  • Deoxygenated blood returns to right atrium, then right ventricle, then to lungs via pulmonary artery.
• Double Circulation: Blood passes through heart twice in one cycle—pulmonary (lungs) and systemic (body organs).
• Arteries vs. Veins:
  • Arteries: Thick, elastic, muscular walls, narrow lumen, carry oxygenated blood (except pulmonary artery), no valves.
  • Veins: Thin, non-elastic walls, wide lumen, carry deoxygenated blood (except pulmonary vein), valves present to prevent backflow.

Excretion: Human and Plant Systems

Excretion is the removal of metabolic waste. Humans and plants use different strategies.

• Human Excretory System: Kidneys, ureters, urinary bladder, urethra.
• Kidney Function: Filters blood, removes nitrogenous wastes (urea, uric acid), forms urine.
• Nephron Structure: Glomerulus (filtration), Bowman's capsule, tubules (reabsorption and secretion).
• Urine Formation Steps:
  1. Glomerular filtration: Initial filtrate contains glucose, amino acids, salts, water, nitrogenous wastes.
  2. Reabsorption: Essential substances (glucose, amino acids, water, salts) reabsorbed.
  3. Secretion: Extra salts and water secreted into tubules.
• Plant Excretion:
  • Excess water removed by transpiration.
  • Wastes stored in vacuoles, leaves, resins, gums.
  • Some wastes excreted into soil.

Control and Coordination: Nervous and Hormonal Systems

Control and coordination are managed by the nervous system and hormones. The nervous system includes the brain, spinal cord, and nerves.

• Nervous System Parts:
  • Central Nervous System (CNS): Brain and spinal cord.
  • Peripheral Nervous System: Somatic (voluntary), autonomic (involuntary), cranial nerves (12 pairs), spinal nerves (spread throughout body).
• Brain Functions:
  • Forebrain: Thinking, memory, emotions, voluntary actions.
  • Midbrain: Connects sensory inputs, controls reflexes.
  • Hindbrain: Cerebellum (balance, posture, coordination), medulla (involuntary actions like heartbeat, breathing).
• Neuron Structure: Dendrites (receive signals), cell body, axon (transmits signal), nerve endings.
• Reflex Actions: Sudden, automatic responses not involving thinking; controlled by spinal cord, not brain.
• Synapse: Gap between two neurons where impulse transmission occurs.
• Hormones:
  • Pancreas: Secretes insulin.
  • Thyroid: Secretes thyroxine (requires iodine).
  • Plant hormones: Gibberellin (stem growth), cytokinins (cell division), abscisic acid (inhibits growth, wilting).

Reproduction: Methods and Structures

Reproduction ensures continuity of life. It can be asexual or sexual, with various methods in different organisms.

• Asexual Reproduction in Unicellular Organisms:
  • Binary fission: Cell splits into two equal parts (e.g., amoeba).
  • Multiple fission: Cell splits into many daughter cells (e.g., Plasmodium).
  • Budding: Small bud forms and separates (e.g., yeast).
  • Spore formation: Spores released from sporangia (e.g., Rhizopus).
• Vegetative Propagation: New plants from leaves (e.g., Bryophyllum).
• Sexual Reproduction in Plants:
  • Flower structure: Pistil (female part—stigma, style, ovary), ovary contains ovules.
  • After fertilization: Ovary becomes fruit, ovule becomes seed.
  • Unisexual flowers: Only male or female reproductive organ (e.g., papaya, watermelon).
  • Bisexual flowers: Both male and female organs (e.g., rose, lily).
• Pollination Agents: Wind, water, animals.
• Human Reproductive System:
  • Testes: Produce sperm and testosterone.
  • Seminal vesicles and prostate gland: Secrete fluid for sperm transport (forms semen).
  • Contraceptive methods: Physical barriers (condoms), chemical (oral pills), surgical (tubectomy, vasectomy), intrauterine devices (Copper-T).
  • Sexually transmitted diseases: HIV/AIDS, syphilis, gonorrhea.

Heredity and Genetics

Heredity deals with the transmission of traits from parents to offspring. Mendel's experiments established basic principles.

• Mendel's Experiments: Studied seven contrasting traits in pea plants (seed color, seed shape, pod color, pod shape, flower color, flower position, plant height).
• Dominant and Recessive Traits: Demonstrated using monohybrid cross (tall × short plants; F$_1$ all tall, F$_2$ 3 tall:1 short).
• Phenotypic Ratio: 3:1 in F$_2$ generation.
• Genotypic Ratio: 1:2:1 in F$_2$ generation.
• Dihybrid Cross: Two traits (e.g., round green × wrinkled yellow seeds); traits inherited independently (law of independent assortment).
• Sex Chromosomes: Humans have 23 pairs; one pair is sex chromosomes (XX in females, XY in males).
• Sex Determination: Child's sex depends on father's chromosome (X or Y).

Environment and Ecosystem

The environment includes all living and non-living components. Ecosystems are classified as natural or artificial.

• Natural Ecosystem Examples: Pond, grassland.
• Trophic Levels:
  • Producers (first level): Grass, wheat, mango.
  • Herbivores (second level): Goat, insects.
  • Carnivores (third level): Humans, fish, snakes.
• Energy Flow:
  • Only 1% of sunlight is captured by leaves and converted to food energy.
  • Only 10% of energy is transferred to the next trophic level.
• Decomposers: Break down complex organic substances into simple inorganic substances, recycle nutrients.
• Food Chain Example: Grass → goat → human.
• Biodegradable Substances: Wood, grass, banana peel.
• Non-biodegradable Substances: Plastic, glass.
• Environment-Friendly Materials: Paper bag, wooden stick; balloons are not environment-friendly.
• CFCs (Chlorofluorocarbon Compounds): Harm ozone layer; increased concentration leads to ozone depletion.

Key Diagrams and Structures

Several diagrams are essential for exam preparation, as repeatedly asked:

• Human Digestive System: Mouth, tongue, esophagus, stomach, liver, pancreas, gall bladder, large intestine, small intestine, anus.

• Human Heart: Four chambers, valves, arteries, veins.

• Neuron: Dendrites, cell body, axon, nerve endings.

• Excretory System: Kidneys, ureters, urinary bladder, urethra.

• Longitudinal Section of Flower: Pistil (stigma, style, ovary), ovules, sepals, petals.

• Dihybrid and Monohybrid Crosses: Punnett squares showing trait inheritance.

• Exam Focus: Practice drawing and labeling these diagrams, and understand the steps and functions associated with each structure.