Study sheet: General Biology Part Two

📋 Course Outline

1. Cell Structure and Organization
2. Membrane Transport and Cell Types
3. Cell Organelles and Functions
4. Cell Division and Reproduction
5. Human and Plant Reproduction
6. Heredity and Genetic Variation
7. Nutrition and Photosynthesis
8. Human Digestion
9. Respiration and Gas Exchange
10. Circulation Blood and Excretion
11. Blood Cells and Plasma
12. Blood Groups and Immunity
13. Excretion and Kidney Function
14. Nervous System and Brain
15. Plant Hormones
16. Human Endocrine Glands
17. Classification of Living Organisms
18. Plant Roots and Animal Diversity

📖 1. Cell Structure and Organization

🔑 Key Concepts & Definitions

• Cell organelles : specialized components within a cell that perform specific functions
• Protoplasm : consists of the cytoplasm and nucleus and contains proteins and other essential molecules

📝 Essential Points

• Human red blood cells are about 7.0 micrometres in diameter, mycoplasma cells are about 0.3 micrometres long, bacteria may be 3–5 micrometres long, and the ostrich egg is the largest isolated single cell.

💡 Memory Hook

A cell as a tiny city with a membrane boundary, nucleus headquarters, cytoplasm, and specialized organelles.

📖 2. Membrane Transport and Cell Types

🔑 Key Concepts & Definitions

• Diffusion : the movement of substances from a region of higher concentration to a region of lower concentration
• Osmosis : the movement of water from higher water concentration to lower water concentration through a semipermeable membrane

📝 Essential Points

📌 In a hypotonic medium a cell gains water and swells, in a hypertonic medium it loses water and shrinks, and in an isotonic medium there is no net movement of water and the cell remains the same.

📌 Active transport uses ATP to move ions or molecules against their concentration gradient, whereas passive transport moves molecules along the gradient without this energy-dependent mechanism.

💡 Memory Hook

Diffusion moves solutes high → low, whereas osmosis moves water through a semipermeable membrane.

📖 3. Cell Organelles and Functions

🔑 Key Concepts & Definitions

• Cell membrane : a selectively permeable phospholipid bilayer containing proteins, cholesterol, and carbohydrates that controls entry and exit of materials
• Nucleus : a double-membrane organelle containing chromosomes and controlling cellular reproduction and other cellular activities
• Mitochondria : double-membrane organelles with their own DNA and ribosomes that generate ATP for cellular activities

📝 Essential Points

• Ribosomes are made of RNA and protein and synthesize proteins by reading messenger RNA; eukaryotic cytoplasmic ribosomes are 80S, whereas prokaryotic ribosomes are 70S.

💡 Memory Hook

ER makes, Golgi modifies and ships, lysosomes digest, mitochondria energize.

📖 4. Cell Division and Reproduction

🔑 Key Concepts & Definitions

• Mitosis : cell division in which one mother cell forms two genetically identical daughter cells with the same chromosome number
• Meiosis : consists of two consecutive divisions and produces four daughter cells containing half the chromosome number of the mother cell

★ Must-know

📌 Asexual reproduction involves one parent and produces genetically identical offspring without gametes or fertilization, whereas sexual reproduction involves gametes, fertilization, and variation.

Further detail

• 🔄 The stages of mitosis are:
  1. prophase
  2. metaphase
  3. anaphase
  4. telophase
  5. cytokinesis

💡 Memory Hook

Mitosis produces two identical cells, whereas meiosis produces four haploid cells.

📖 5. Human and Plant Reproduction

🔑 Key Concepts & Definitions

• Fertilization : the fusion of the male germ cell from pollen with the female gamete in the ovule to form a zygote

★ Must-know

📌 Self-pollination transfers pollen within the same flower, whereas cross-pollination transfers pollen from one flower to another.

Further detail

• The main flower structures and functions are:

  • anther produces pollen
  • filament supports the anther
  • ovary contains ovules
  • style is the elongated middle part
  • stigma is the terminal part

• After fertilization, the ovule develops into a seed and the ovary grows and ripens into a fruit.

💡 Memory Hook

Pollination → fertilization → zygote → embryo → seed or offspring.

📖 6. Heredity and Genetic Variation

🔑 Key Concepts & Definitions

• Gene : the basic physical and functional unit of heredity

★ Must-know

📌 A genotype is an individual's genetic code, whereas a phenotype is the individual's observable traits.

• In a monohybrid cross of homozygous tall and dwarf pea plants, the F1 offspring are heterozygous tall and the F2 phenotypic ratio is 3:1 while the genotypic ratio is 1:2:1.

Further detail

• Gregor Mendel is identified as the father of genetics and used pea plants for heredity experiments.

💡 Memory Hook

Genotype is the genetic code, whereas phenotype is the observable trait.

📖 7. Nutrition and Photosynthesis

★ Must-know

📌 Autotrophic organisms make their own food using light or chemicals, whereas heterotrophic organisms obtain food from other organisms or organic matter.

• Photosynthesis converts carbon dioxide and water into carbohydrates in the presence of sunlight and chlorophyll, releasing oxygen.

• Stomata allow gaseous exchange in leaves, and guard cells control the opening and closing of each pore.

Further detail

📌 Photoautotrophs use sunlight to make food, whereas chemoautotrophs use energy from chemical reactions.

💡 Memory Hook

Light absorbed by chlorophyll drives conversion of carbon dioxide and water into stored carbohydrates.

📖 8. Human Digestion

📝 Essential Points

• 🔄 The stages of human nutrition are:

  1. ingestion
  2. digestion
  3. absorption
  4. assimilation
  5. egestion

• Salivary amylase begins starch digestion in the mouth, while hydrochloric acid in the stomach kills harmful bacteria and converts pepsinogen into pepsin.

• Bile salts emulsify fats into smaller globules, trypsin digests proteins, and lipase digests emulsified fats in the small intestine.

• The small intestine is the site of complete digestion of carbohydrates, proteins, and fats, and its villi increase the surface area for absorption.

💡 Memory Hook

Ingestion → digestion → absorption → assimilation → egestion.

📖 9. Respiration and Gas Exchange

★ Must-know

📌 Breathing is the physical inhalation and exhalation of air without energy production, whereas respiration is the chemical breakdown of glucose that produces ATP.

📌 Aerobic respiration uses oxygen and produces carbon dioxide, water, and more energy, whereas anaerobic respiration occurs without oxygen and produces less energy or lactic acid or ethanol and carbon dioxide.

• Glycolysis breaks a six-carbon glucose molecule into the three-carbon molecule pyruvate in the cytoplasm.

Further detail

• Aerobic respiration releases up to 38 ATP molecules, described in the source as 19 times more energy than anaerobic respiration.

💡 Memory Hook

Breathing exchanges gases without producing energy, whereas respiration breaks down glucose to produce ATP.

📖 10. Circulation Blood and Excretion

★ Must-know

• 🔄 The circulation route is:

  1. right atrium
  2. right ventricle
  3. pulmonary arteries
  4. lungs
  5. pulmonary veins
  6. left atrium
  7. left ventricle
  8. aorta

• Red blood cells contain hemoglobin, have a biconcave shape, circulate for up to 120 days, and carry oxygen from the lungs to body tissues.

📌 Ammonotelic organisms excrete ammonia, ureotelic organisms excrete urea, and uricotelic organisms excrete uric acid.

Further detail

• The normal white blood cell count is 4,000–10,000 per microlitre, and white blood cells defend the body against infection.

• Plasma contributes about 55% of total blood volume and transports blood cells, hormones, nutrients, waste products, and other substances.

💡 Memory Hook

Heart → arteries → capillaries → veins → heart.

📖 11. Blood Cells and Plasma

🔑 Key Concepts & Definitions

• White blood cells : Colorless blood cells lacking hemoglobin that help the body fight infections and other diseases.
• Platelets : Small colorless cell fragments made in bone marrow that help seal blood vessels and form clots.
• Plasma : The light amber liquid component of blood that contributes 55% of total blood volume and transports cells, hormones, nutrients, wastes, and other substances.

★ Must-know

📌 White blood cells are divided into granulocytes and agranulocytes, while neutrophils and monocytes are phagocytic cells that destroy infectious agents.

Further detail

• A normal white blood cell count is between 4,000 and 10,000 cells per microliter, and a white blood cell typically lives for 13–20 days.

• The normal platelet range is 1.5 lakh to 3.5 lakh platelets per microliter, and a low platelet count is called thrombocytopenia.

💡 Memory Hook

WBCs defend, platelets clot, and plasma transports

📖 12. Blood Groups and Immunity

🔑 Key Concepts & Definitions

• Antigen : A substance capable of inducing an immune response through the production of antibodies.
• Active immunity : Develops when the body produces its own antibodies after exposure to an antigen and is generally a slow process.

📝 Essential Points

📌 An antibody is a plasma protein produced in response to an antigen, whereas an antigen is the substance that induces the immune response.

• The Rh(D) antigen is present on red blood cells in Rh-positive people and absent in Rh-negative people.

• AB-positive blood is known as the universal recipient type, whereas O-type blood is known as the universal donor type.

💡 Memory Hook

Antigens identify; antibodies respond

📖 13. Excretion and Kidney Function

🔑 Key Concepts & Definitions

• Excretion : The process by which the body removes metabolic wastes such as excess water, salts, and urea.

★ Must-know

• Nephrons are the functional units of the kidneys, and urea is formed in the liver.

• 🔄 Urine follows this route:

  1. passes from each kidney through a ureter
  2. is stored in the urinary bladder
  3. leaves through the urethra during micturition

Further detail

• An adult typically excretes 1–1.5 liters of urine per day, and urochrome gives urine its yellow color.

💡 Memory Hook

Kidney → ureter → bladder → urethra

📖 14. Nervous System and Brain

🔑 Key Concepts & Definitions

• Central nervous system : Consists of the brain and spinal cord and is protected by the skull and vertebral column.
• Peripheral nervous system : Consists of all nerves in the body and relays information between the brain, spinal cord, and organs.
• Synapse : The gap between two neurons, across which neurotransmitters allow neurons to communicate.

📝 Essential Points

• In a reflex action, a stimulus is detected by a receptor, carried by a sensory neuron to the spinal cord, relayed to a motor neuron, and followed by an effector response.

• The cerebrum is the largest part of the brain and controls speech, thought, emotions, reading, writing, learning, and muscle functions.

💡 Memory Hook

Stimulus → receptor → sensory neuron → CNS → motor neuron → effector

📖 15. Plant Hormones

🔑 Key Concepts & Definitions

• Auxin : Synthesized at the shoot tip, promotes cell elongation, supports flowering, controls xylem differentiation, and can induce parthenocarpy.

★ Must-know

• When light comes from one side of a shoot, auxin diffuses toward the shady side and promotes growth there.

• Abscisic acid is a stress hormone that inhibits growth and seed germination and promotes seed maturation, dormancy, and leaf wilting.

Further detail

• Gibberellins promote stem growth, germination, flowering, fruit elongation, and bolting before flowering.

• Cytokinins promote cell division, delay aging, and help overcome apical dominance.

• Ethylene promotes fruit ripening, senescence, root growth, root-hair formation, and the apical hook in dicot seedlings.

💡 Memory Hook

Promoters stimulate growth, whereas inhibitors induce dormancy

📖 16. Human Endocrine Glands

📝 Essential Points

📌 Exocrine glands secrete substances through ducts onto body surfaces, whereas endocrine glands secrete hormones directly into the bloodstream.

• The pineal gland secretes melatonin, which regulates the body's 24-hour rhythm, including the sleep–wake cycle and temperature rhythms.

• Pituitary hormones include:

  • growth hormone
  • prolactin
  • thyroid-stimulating hormone
  • adrenocorticotrophic hormone
  • luteinizing hormone
  • follicle-stimulating hormone
  • melanocyte-stimulating hormone
  • oxytocin
  • vasopressin

• Adrenaline increases heartbeat, the strength of heart contraction, and the rate of respiration during stressful or dangerous situations.

• Thyroxine regulates carbohydrate, protein, and fat metabolism, and iodine is necessary for its production.

• Insulin decreases blood glucose levels, whereas glucagon increases them; both hormones are produced by the pancreatic islets.

💡 Memory Hook

Exocrine glands use ducts; endocrine glands release hormones into blood

📖 17. Classification of Living Organisms

🔑 Key Concepts & Definitions

• Angiosperms : Flowering vascular plants whose seeds are enclosed within fruits.
• Fungi : Multicellular eukaryotic organisms with chitinous cell walls that obtain nutrition saprophytically and do not perform photosynthesis.

📝 Essential Points

• Taxonomy is the science of naming, describing, and classifying organisms, and Carl Linnaeus is called the Father of Taxonomy.

• Charles Darwin first described the idea of evolution in 1859 in his book “THE ORIGIN OF SPECIES”.

📌 Prokaryotes lack a true nucleus, whereas eukaryotes possess cells with a nucleus; Monera contains prokaryotes while Protista contains unicellular eukaryotes.

💡 Memory Hook

Monera → Protista → Fungi → Plantae → Animalia

📖 18. Plant Roots and Animal Diversity

🔑 Key Concepts & Definitions

• Animalia : Multicellular eukaryotic heterotrophs without cell walls that exhibit an organ-system level of organization.
• Biotechnology : Uses living cells or biological molecules to generate useful products for human benefit.
• Trophic level : An organism's position in a food chain according to its feeding relationship and nutritional source.

★ Must-know

📌 A taproot system has one main root growing vertically downward with smaller lateral roots, whereas a fibrous root system has many similarly sized branching roots.

• Root functions include:

  • absorb water and nutrients
  • anchor plants
  • transport materials
  • store reserve food and carbohydrates

• Monocotyledons have one seed leaf, whereas dicotyledons have two seed leaves.

📌 Vertebrates have a vertebral column, whereas invertebrates do not; vertebrate classes include fish, amphibians, reptiles, birds, and mammals.

📌 Congenital diseases are present at birth and inherited, whereas acquired diseases develop after birth and are not inherited.

• Single-gene inheritance results from a mutation in one gene, chromosomal disorders result from changes in chromosome number or structure, and multifactorial inheritance combines environmental factors with mutations in multiple genes.

• Mitochondrial DNA is inherited from the mother, and mitochondrial inheritance results from mutations in non-nuclear mitochondrial DNA.

• Recombinant DNA technology isolates a gene of interest, inserts it into a vector, introduces the modified vector into a host cell, multiplies the host cells, and increases production of the required protein.

• The trophic levels are:

  • first: producers
  • second: primary consumers
  • third: secondary consumers
  • fourth: tertiary or top consumers

• Only 10% of energy is transferred from one trophic level to the next, so pyramids of energy are always upright.

• Homologous structures have similar anatomy but different functions and indicate common ancestry, whereas analogous structures have different anatomy but similar functions and do not arise from common ancestry.

• Mutualism benefits both species, commensalism benefits one without affecting the other, parasitism benefits one while harming the other, and competition negatively affects organisms competing for limited resources.

Further detail

• Arthropods have jointed appendages, an exoskeleton, and segmented bodies and form the largest phylum in the animal kingdom.

💡 Memory Hook

Monocots have one seed leaf; dicots have two

📊 Synthesis Tables

Mitosis and Meiosis

Feature	Mitosis	Meiosis
Number of divisions	One	Two consecutive divisions
Daughter cells	Two	Four
Chromosome number	Same as mother cell	Half that of mother cell
Genetic outcome	Identical cells	Variation-producing cells

Aerobic and Anaerobic Respiration

Feature	Aerobic	Anaerobic
Oxygen	Required	Absent
Main products	Carbon dioxide, water, and energy	Lactic acid or ethanol, carbon dioxide, and energy
Energy yield	Up to 38 ATP molecules	Less energy
Location	Cytoplasm and mitochondria	Cytoplasm only