Life Processes

A comprehensive set of vocabulary flashcards covering the key concepts of life processes, including nutrition, respiration, transportation, and excretion in both humans and plants as described in Chapter 5.

Life processes

The processes which together perform the maintenance job of living organisms, preventing damage and break-down even when the organism is at rest.

Nutrition

The process of transferring a source of energy from outside the body (food) to the inside.

Respiration

The process of acquiring oxygen from outside the body and using it in the process of break-down of food sources for cellular needs.

Excretion

The biological process involved in the removal of harmful metabolic wastes, such as nitrogenous materials, from the body.

Autotrophs

Organisms that use simple food material obtained from inorganic sources in the form of carbon dioxide and water, such as green plants and some bacteria.

Heterotrophs

Organisms that utilize complex substances which must be broken down into simpler ones; their survival depends directly or indirectly on autotrophs.

Enzymes

Bio-catalysts used by organisms to break down complex substances into simpler ones for upkeep and growth.

Photosynthesis

The process by which autotrophs take in carbon dioxide and water and convert them into carbohydrates in the presence of sunlight and chlorophyll.

Starch

The form in which carbohydrates not used immediately by plants are stored, serving as an internal energy reserve.

Glycogen

The form in which some energy derived from food is stored in the human body.

Chloroplasts

Cell organelles that contain chlorophyll and appear as green dots in a leaf cross-section.

Stomata

Tiny pores present on the surface of the leaves through which massive amounts of gaseous exchange and water loss occur.

Guard cells

Specialised cells that regulate the opening and closing of the stomatal pore by swelling or shrinking.

Saliva

A fluid secreted by salivary glands that wets food and contains the enzyme salivary amylase.

Salivary amylase

An enzyme in saliva that breaks down starch, a complex molecule, into simple sugar.

Peristaltic movements

Rhythmic contractions of the muscles along the lining of the alimentary canal that push food forward.

Pepsin

A protein-digesting enzyme released by the gastric glands in the stomach.

Sphincter muscle

A muscle that regulates the exit of food from the stomach into the small intestine and also controls waste exit at the anus.

Villi

Finger-like projections on the inner lining of the small intestine that increase surface area for absorption and are richly supplied with blood vessels.

Dental plaque

Masses of bacterial cells together with food particles that stick to teeth, preventing saliva from neutralising acids.

Pyruvate

A three-carbon molecule produced by the initial break-down of glucose in the cytoplasm.

Anaerobic respiration

The process of breaking down pyruvate in the absence of oxygen, resulting in ethanol and carbon dioxide in yeast fermentation.

Aerobic respiration

The process of breaking down pyruvate in the presence of oxygen in the mitochondria to give carbon dioxide, water, and a large amount of energy.

Lactic acid

A three-carbon molecule formed from the break-down of pyruvate in muscle cells when there is a lack of oxygen, causing cramps.

ATP (Adenosine Triphosphate)

The energy currency for most cellular processes; its terminal phosphate linkage release involves $30.5\,kJ\,mol^{-1}$.

Alveoli

Balloon-like structures at the end of the respiratory passage that provide a surface for gas exchange.

Haemoglobin

The respiratory pigment in human beings found in red blood corpuscles which has a high affinity for oxygen.

Plasma

The fluid medium of blood in which cells are suspended and which transports food, carbon dioxide, and nitrogenous wastes in dissolved form.

Systolic pressure

The pressure of blood inside the artery during ventricular contraction (ventricular systole), normally about $120\,mm \text{ of Hg}$.

Diastolic pressure

The pressure of blood inside the artery during ventricular relaxation (ventricular diastole), normally about $80\,mm \text{ of Hg}$.

Arteries

Thick-walled, elastic vessels that carry blood away from the heart to various organs under high pressure.

Capillaries

The smallest blood vessels with walls one-cell thick, where the exchange of material between blood and surrounding cells occurs.

Platelets

Blood cells that circulate around the body and plug leaks by helping to clot blood at points of injury.

Lymph

A colourless fluid containing less protein than plasma that carries digested fat and drains excess fluid from intercellular spaces back to the blood.

Xylem

Vascular tissue in plants that move water and minerals obtained from the soil upward from the roots.

Phloem

Vascular tissue in plants that transports products of photosynthesis from the leaves to other parts of the plant.

Transpiration

The loss of water in the form of vapour from the aerial parts of a plant, helping in suction and temperature regulation.

Translocation

The transport of soluble products of photosynthesis in the phloem using energy from ATP.

Nephrons

The basic filtration units in the kidney, consisting of a cluster of thin-walled capillaries associated with a cup-shaped Bowman's capsule.

Hemodialysis

The process of using an artificial kidney to remove nitrogenous waste products from the blood in case of kidney failure.