Grade 11 Biology Review Flashcards

Vocabulary flashcards covering Grade 11 Biology topics including plant and animal transport, respiration, excretion, homeostasis, growth, and responses based on Zambian O-level syllabus material.

Vascular System

The transport system in flowering plants consisting of xylem and phloem, which are closely associated with cambium.

Cambium

A meristematic tissue in plants that carries out cell division to produce new cells, including xylem and phloem cells.

Root Hair Cell

An elongated outgrowth of an epidermal cell near root tips adapted for absorbing water by osmosis and mineral salts by active transport.

Transpiration Stream

The continuous movement of water up the plant through xylem vessels.

Transpiration

The diffusion of water vapour from plant leaves to the atmosphere through stomata.

Capillarity

The movement of water into narrow tubes or openings resulting from cohesion and adhesion forces.

Root Pressure

Pressure created in xylem vessels due to the osmotic gain of water by roots, pushing water upward.

Guttation

The loss of water drops from leaf tips and margins through special openings called hydathodes.

Wilting

The sagging of delicate plant parts such as leaves, flowers, and young stems occurring when the transpiration rate exceeds water uptake.

Potometer

An instrument used to measure the rate of transpiration in a plant shoot.

Translocation

The movement of manufactured food (mainly sucrose and amino acids) from the source to sink sites through phloem.

Root Tuber

A fibrous root swollen with stored food, such as in the sweet potato (Ipomea batatas).

Stem Tuber

An underground stem swollen with stored food, such as in the Irish potato (Solanum tuberosum).

Bulb

A plant storage organ made of underground fleshy leaves growing from a short stem, such as an onion (Allium sp).

Rhizome

A swollen underground horizontal stem used for food storage, such as ginger.

Corm

A swollen underground, vertical short stem, such as in Crocus species.

Cardiac Muscle

The type of muscle in the heart wall that is myogenic, non-fatiguing, and contains branched single-nucleated cells.

Sinoatrial Node (SAN)

A patch of cardiac muscle in the right atrium (pacemaker) where the self-stimulating impulse for heart contraction originates.

Systole

The contraction phase of the cardiac muscle during the cardiac cycle.

Diastole

The relaxation phase of the cardiac muscle during the cardiac cycle.

Double Circulation

A circulation system where blood passes through the heart twice during one complete journey around the body.

Pulmonary Circulation

The flow of blood from the right ventricle to the lungs through the pulmonary artery and back to the left atrium through the pulmonary vein.

Systemic Circulation

The flow of blood from the left ventricle to the rest of the body through the aorta and back to the right atrium through the venacava.

Pulse

A wave of pressure created in the arteries by a heart beat.

Atheroma

An accumulation of fatty material, mainly cholesterol, in the walls of coronary arteries.

Thrombosis

The blockage of blood vessels by a mixture of blood clots, fatty material, and fibres.

Arteries

Thick-walled blood vessels with narrow lumens that carry oxygenated blood away from the heart at high pressure (except pulmonary artery).

Veins

Thin-walled blood vessels with wide lumens and valves that carry deoxygenated blood towards the heart at low pressure (except pulmonary vein).

Capillaries

The smallest blood vessels, one cell thick, that form capillary beds in tissues to allow material exchange between blood and cells.

Tissue Fluid

Fluid formed when blood plasma is filtered out of capillaries into tissue spaces, serving to bathe cells, thermoregulate, and exchange materials.

Erythrocytes

Biconcave disc-shaped red blood cells lacking a nucleus, containing haemoglobin for transporting oxygen.

Haemoglobin

A red iron-containing pigment in red blood cells that reversibly combines with oxygen to form oxyhaemoglobin.

Phagocytes

White blood cells with lobed nuclei and amoeboid movement that defend the body by engulfing and digesting germs.

Lymphocytes

White blood cells with large nuclei and thin cytoplasm that produce antibodies and antitoxins to defend the body.

Thromboplastin

An enzyme released by exposed platelets at a damaged tissue site that converts prothrombin into active thrombin.

Fibrin

An insoluble protein formed from fibrinogen during clotting that creates a mesh over a wound to trap blood cells.

Universal Donor

Blood group O, because its red cell membranes lack A and B antigens, preventing recipient antibodies from attacking it.

Universal Recipient

Blood group AB, because its blood plasma lacks anti-A and anti-B antibodies, allowing it to receive blood from any blood group.

Haemolytic Disease

A severe condition in newborns caused by maternal anti-rhesus antibodies crossing the placenta to attack rhesus-positive fetal blood.

Sickle Cell Anaemia

An inherited disease caused by abnormal haemoglobin, leading red blood cells to become sickle-shaped under low oxygen levels.

Haemophilia

An inherited bleeding disorder caused by the absence of blood clotting proteins known as factor VIII and factor IX.

Lymphatic System

A transport and defense system made of vessels, lymph fluid, and organs like the spleen that drains excess tissue fluid and absorbs fats.

Respiration

The release of energy from food substances in living cells.

Aerobic Respiration

The release of energy from food in living cells in the presence of oxygen, yielding carbon dioxide, water, and energy ($2880\,kJ$ per mole of glucose).

Alcoholic Fermentation

Anaerobic respiration carried out by yeast catalyzed by zymase, producing alcohol, carbon dioxide, and $210\,kJ$ per mole of glucose.

Lactic Fermentation

Anaerobic respiration in muscle cells during exercise, producing lactic acid and $150\,kJ$ per mole of glucose.

Oxygen Debt

The total amount of oxygen required after exercise to break down accumulated lactic acid into carbon dioxide and water.

Adenosine Triphosphate (ATP)

An energy storage molecule produced from ADP and inorganic phosphate during respiration to provide usable energy for living cells.

Gaseous Exchange

The diffusion of oxygen into the blood and carbon dioxide out of the blood across a specialized gaseous exchange surface.

Tidal Volume

The volume of air breathed in or out in one normal breath while resting (approximately $0.5\,dm^3$ in humans).

Vital Capacity

The maximum volume of air breathed out after a forced inspiration (approximately $3.5\,dm^3$ in humans).

Residual Volume

The volume of air that remains in the lungs after forced expiration (approximately $1.5\,dm^3$) to prevent lung collapse.

Bronchitis

Inflammation of air passages caused when tar immobilizes cilia, allowing mucus and germs to accumulate.

Emphysema

The weakening and bursting of alveoli caused by irritation from tar, reducing the surface area for gaseous exchange.

Spiracles

External breathing openings located in the thorax and abdomen of insects that connect to tracheae.

Excretion

The removal of toxic metabolic waste products from the bodies of living organisms.

Nephron

The basic functional unit of the kidney responsible for filtering blood and forming urine.

Ultrafiltration

The filtration under high pressure of small molecules from the glomerulus into the Bowman's capsule of a nephron.

Selective Reabsorption

The reabsorption of useful substances (glucose, water, salts) from the glomerular filtrate back into the bloodstream in the renal tubule.

Osmoregulation

The regulation of water levels and solute concentration in body fluids.

Antidiuretic Hormone (ADH)

A hormone produced by the pituitary gland that increases water reabsorption in the renal tubules and loop of Henle when body water is low.

Counter-Current Flow

The flow of blood and dialysis fluid in opposite directions in a dialysis machine to maintain a concentration gradient for efficient diffusion.

Homeostasis

The maintenance of a constant internal environment within an organism.

Thermoregulation

The maintenance of a constant body temperature (around $37\,^\circ\text{C}$ in humans).

Vasoconstriction

The narrowing of skin arterioles in cold conditions to reduce blood flow near the skin surface and minimize heat loss.

Vasodilation

The widening of skin arterioles in hot conditions to increase blood flow near the skin surface and promote heat loss.

Insulin

A hormone secreted by beta cells of the Islets of Langerhans that lowers blood glucose by converting excess glucose to glycogen and fats.

Glucagon

A hormone secreted by alpha cells of the Islets of Langerhans that increases blood glucose by converting stored glycogen into glucose.

Diabetes Mellitus

A disease caused by insufficient insulin production, characterized by hyperglycemia, glucosuria, excessive thirst, and loss of weight.

Primary Growth

An increase in the length of plant shoots and roots initiated by apical meristems.

Secondary Growth

An increase in the width or girth of plant shoots and roots initiated by cambial meristems.

Epigeal Germination

A type of germination where cotyledons are pushed above ground due to the elongation of the hypocotyl.

Hypogeal Germination

A type of germination where cotyledons remain underground due to the elongation of the epicotyl.

Seed Dormancy

A state during which a viable seed carries out minimum metabolism and does not germinate.

Scarification

The physical or mechanical destruction of a hard seed coat to make it permeable to water and oxygen.

Vector

Any organism that carries and transmits parasites or pathogens from one host to another.

Tropism

The growth response of a plant part towards or away from a directional stimulus.

Auxins

Plant growth substances produced at shoot and root tips that promote cell elongation in shoots and inhibit cell growth in roots.

Taxic Response

A directional movement response of an entire invertebrate organism towards or away from a stimulus.

Hormone

A chemical secreted by a ductless gland into the blood that exerts specific effects on target organs before being destroyed by the liver.

Adrenaline

A hormone produced by the adrenal glands that prepares the body for action during anger, fear, or excitement.

Synapse

The functional junction between two neurones where impulses are transmitted across a synaptic gap via chemical neurotransmitters.

Reflex Action

An automatic and stereotyped rapid response to a stimulus.

Medulla Oblongata

The hindbrain section controlling automatic vital processes including heart rate, breathing rate, swallowing, and blood pressure regulation.

Cerebrum

The largest part of the brain that serves as the centre for intelligence, memory, language, consciousness, and voluntary actions.