Form Two Biology: Transport, Respiration, Gaseous Exchange, and Homeostasis

Comprehensive practice flashcards covering Form Two Biology topics including plant and animal transport, the mammalian circulatory system, aerobic and anaerobic respiration, gaseous exchange systems, and the mechanisms of excretion and homeostasis.

Transport

The movement of substances within an organism.

Xylem

A specialized transport tissue in higher plants responsible for transporting water and mineral salts.

Phloem

A specialized transport tissue in higher plants responsible for transporting dissolved food substances like sugars.

Piliferous layer

The outermost layer of young roots whose cells give rise to root hairs for efficient absorption.

Endodermis

A single layer of cells in the root, also known as the starch sheath, containing a casparian strip that controls the entry of water and mineral salts into xylem vessels.

Sclerenchyma

Cells thickened by the deposition of lignin that provide support to the plant.

Transpiration

The process by which plants lose water in the form of water vapour into the atmosphere through stomata, cuticle, and lenticels.

Tracheids

Xylem cells with perforated cross-walls, lignin-deposited tapering ends, and a narrower lumen than xylem vessels.

Transpiration pull

A force created in the leaves by the evaporation of water that pulls water up from the xylem vessels in the stem and root.

Cohesion

The attraction between water molecules themselves.

Adhesion

The attraction between water molecules and the walls of xylem vessels.

Capillarity

The ability of water to rise in fine capillary tubes due to surface tension.

Translocation

The movement of soluble organic products of photosynthesis, such as glucose and amino acids, within a plant via the phloem.

Companion Cells

Cells in the phloem with large nuclei and many mitochondria that generate energy required for translocation.

Open Circulatory System

A system where the heart pumps blood into vessels that open into body spaces known as haemocoel, bringing blood into direct contact with tissues.

Closed Circulatory System

A system where blood is confined within blood vessels and does not come into direct contact with tissues, found in vertebrates and annelids.

Pulmonary Circulation

The movement of blood from the heart to the lungs through the pulmonary artery and back to the heart through the pulmonary vein.

Systemic Circulation

The movement of oxygenated blood from the heart to body tissues through the aorta and back as deoxygenated blood through the vena cava.

Systole

The phase of the heartbeat where ventricular muscles contract, forcing blood out of the heart.

Diastole

The phase of the heartbeat where ventricular muscles relax and the chambers fill with blood.

Myogenic

The property of the heart muscle whereby rhythmic contraction arises from within the muscle itself without nervous stimulation.

Thrombosis

The formation of a clot in the blood vessels, such as coronary thrombosis which can lead to a heart attack.

Erythrocytes

Red blood cells, which are circular biconcave discs without nuclei, containing haemoglobin for oxygen transport.

Leucocytes

White blood cells that possess a nucleus and defend the body against disease through phagocytosis or antibody production.

Rhesus factor

An antigen present in the red blood cells of individuals who are Rhesus positive ($Rh+$).

Immune response

The production of antibodies by the body in response to the introduction of a foreign material known as an antigen.

Respiration

The process by which energy is liberated from organic compounds such as glucose.

Adenosine triphosphate (ATP)

An energy-rich compound consisting of adenine, ribose-sugar, and three phosphate groups, used as a direct energy source for cellular activities.

Glycolysis

The initial stage of glucose breakdown in the cytoplasm where glucose is converted into pyruvic acid, yielding a net of $2$ molecules of $ATP$.

Kreb's citric acid cycle

A cyclical series of reactions in the mitochondria occurring in the presence of oxygen, resulting in the production of $36$ molecules of $ATP$, carbon (IV) oxide, and water.

Oxygen debt

The extra oxygen the body takes in after vigorous exercise to break down accumulated lactic acid into carbon (IV) oxide and water.

Respiratory Quotient (RQ)

The ratio calculated as: $R.Q. = \frac{\text{Amount of carbon (IV) oxide produced}}{\text{Amount of oxygen used}}$

Gaseous exchange

The movement of oxygen and carbon (IV) oxide between the cells of organisms and the environment across a respiratory surface.

Pneumatophores

Breathing roots in mangrove plants that project above ground level and possess pores for gaseous exchange.

Spiracles

Tiny pores on the sides of an insect's body segments through which the tracheal system communicates with the atmosphere.

Counter Current Flow

An adaptation in bony fish where blood in the gill filaments flows in the opposite direction to water to ensure maximum diffusion of oxygen.

Tidal volume

The volume of air exchanged during normal breathing, which is about $500\,cm^3$ in an adult human.

Residual volume

The amount of air that always remains in the lungs even after a forced expiration.

Excretion

The process by which living organisms separate and eliminate waste products of metabolism from body cells.

Egestion

The removal of undigested materials from the alimentary canals of animals.

Nephron

The functional unit of the kidney, consisting of a Bowman's capsule, glomerulus, and specialized tubules for urine formation.

Ultra-filtration

The process in the glomerulus where pressure forces small molecules like urea, glucose, and salts into the Bowman's capsule.

Homeostasis

The maintenance of a constant internal environment, such as regulating temperature, osmotic pressure, and $pH$.

Osmoregulation

The control of salt and water balance in the body to maintain appropriate osmotic pressure.

Anti-diuretic hormone (ADH)

A hormone produced by the pituitary gland that increases the permeability of the kidney's collecting duct and distal convoluted tubule to water.

Detoxification

The process in the liver where toxic substances are converted into harmless substances.