Life Science: Comprehensive Biology Lecture Notes

This set covers vocabulary and core concepts from a comprehensive collection of biology notes, including cell biology, nutrition, transport systems, genetics, and biotechnology.

Cell Membrane

A selectively permeable structure made of 2 lipid layers with a protein layer sandwiched in between that selects substances entering and leaving the cell.

Mitochondrion

A cell organelle surrounded by 2 membranes where the inner membrane has folds; it is the site for aerobic respiration and releases energy.

Erythrocytes

Also known as Red Blood Cells, these contain haemoglobin to bind with $O_2$ and move through vessels with a biconcave structure and no nucleus.

Phagocytes

White blood cells that are polymorphs with a lobed nucleus and granular cytoplasm; they engulf and digest bacteria.

Xylem cells

Dead hollow tubes with lignified walls that transport water and dissolved minerals from roots to the top of a plant.

Tissue

A group of similar cells carrying out the same function.

Active Transport

The movement of materials from a region of low concentration to high concentration against the concentration gradient using energy from respiration.

Turgid

The state of a plant cell when turgor pressure builds up inside the cell membrane causing it to stretch and touch the cell wall after being immersed in a dilute solution.

Monera

A kingdom of unicellular organisms such as bacteria and blue-green algae that lack a membrane-enclosed nucleus.

Pathogens

Micro-organisms, such as certain bacteria or viruses, that cause diseases.

Viruses

Non-cellular particles consisting of genetic material ($DNA$ or $RNA$) surrounded by a protein coat called a capsid; they can only reproduce inside living cells.

Plasmodium

A protozoan parasite that causes malaria and is transferred by the female Anopheles mosquito.

Angiosperms

Flowering plants that have a vascular system, cuticles, and ovaries to protect ovules; they are divided into monocotyledons and dicotyledons.

Arthropods

Invertebrates characterized by an exoskeleton made of chitin, a segmented body, and jointed legs.

Anabolic reaction

Biochemical reactions that involve the synthesis of macromolecules from micromolecules, such as joining glucose to make starch.

Denature

The change in the protein structure of an enzyme caused by temperatures above $50^{\circ}\text{C}$, resulting in very slow or stopped chemical reactions.

Optimum pH

The specific pH level at which an enzyme would catalyse a reaction most effectively.

Photosynthesis

The process by which green plants fix complex organic substances like carbohydrates from $CO_2$ and $H_2O$ using sunlight and chlorophyll.

Palisade mesophyll

The main site for photosynthesis in a leaf, consisting of column-shaped cells containing many chloroplasts.

Limiting factor

An environmental factor, such as light intensity or $CO_2$ concentration, that directly affects the rate of a chemical reaction if its quantity is changed.

Chemical digestion

The conversion of large food substances into smaller molecules through the action of enzymes.

Peristalsis

A wave of involuntary muscle contractions that transport contents through a tube-shaped organ like the intestine or oesophagus.

Bile

A greenish fluid produced in the liver and stored in the gall bladder that emulsifies fats in the duodenum.

Villi

Finger-like projections on the inner lining of the ileum that increase surface area for the absorption of digested food.

Deamination

The process in the liver where excess amino acids are broken down into glycogen and urea.

Alveolus

A collapsible air sac in the lung surrounded by capillaries where gaseous exchange occurs.

Vital Capacity

The maximum volume of air that can be exchanged during breathing in and out.

Oxygen Debt

The shortfall of oxygen during vigorous exercise that is repaid by increased $O_2$ intake to oxidize accumulated lactic acid.

Translocation

The movement of organic substances like sucrose through the phloem vessels in plants.

Aorta

The main artery carrying oxygenated blood from the heart to the rest of the body.

Phagocytosis

The action of a phagocyte flowing around, engulfing, and digesting invading bacteria or dead tissue cells.

Leukaemia

Often called cancer of the blood, a condition where large numbers of immature white blood cells are produced, inhibiting red blood cell formation.

Glomerulus

Highly coiled capillaries within the Bowman’s capsule of a nephron where ultrafiltration occurs under high pressure.

Homeostasis

The process of keeping the internal environment of a mammal stable or within narrow limits.

Vasodilation

The increase in diameter of blood vessels in the skin to allow more blood flow near the surface to lose heat when the body is overheating.

Synapse

A very small gap between neurons where neurotransmitters are secreted to restart a nerve impulse in the next cell.

Accommodation

The process of producing a finely focused image on the retina by changing the shape of the lens via the ciliary muscles.

Hormone

A chemical substance produced by a gland and carried in the blood which alters the activity of specific target organs.

Auxin

A plant growth hormone produced in the tips of seedlings that accelerates growth in length and regulates tropic responses.

Pollination

The transfer of pollen grains from the anther to the stigma of a flower.

Testosterone

A male hormone that controls sperm production and the development of secondary sexual characteristics.

Corpus luteum

A solid body formed from a ruptured follicle in the ovary that secretes oestrogen and progesterone to thicken the uterus lining.

Drug Dependence

The inability of body systems to function normally without a drug, often resulting from drug tolerance.

Eutrophication

An ecological process where excess fertilizers in water promote algae growth, leading to oxygen depletion and the death of aquatic animals.

Tendons

Tough structures that connect a bone to a muscle to ensure movement during contraction.

Gene

A basic unit of inheritance made of $DNA$ located at a specific locus on a chromosome.

Mitosis

Cell division occurring in ordinary body cells during growth that results in daughter cells with the same diploid number ($2n$) as the parent cell.

Genotype

The genetic makeup of an individual, determined by the sequence of bases in a $DNA$ strand.

Incomplete dominance

A genetic condition where the heterozygote produces an intermediate phenotype because the dominant allele does not completely mask the recessive one.

Mutation

A sudden change in a gene or chromosome that alters development, often caused by mutagens like radiation or chemicals.

Natural Selection

The process whereby the environment favours organisms with the best-adapted phenotypic variations, also known as 'survival of the fittest'.