Study Guide: Biology Unit 2 for CAPE - Vocabulary Flashcards

Vocabulary flashcards covering Bioenergetics, Biosystems Maintenance, and Applications of Biology for the CAPE Unit 2 curriculum.

Autotrophs

Organisms that use simple inorganic compounds to synthesize complex organic compounds, such as glucose and starch.

Heterotrophs

Organisms that obtain carbon and energy by consuming complex organic compounds, usually by eating other organisms or decaying matter.

Photosynthesis

The process of absorbing light energy to drive the synthesis of simple carbohydrates from carbon dioxide and water.

Respiration

The transfer of chemical energy from complex organic compounds to $ATP$ and heat.

Phototrophs

Organisms that obtain their energy source by absorbing light.

Chemotrophs

Organisms that gain energy from chemical reactions involving elements or simple inorganic/organic compounds.

ATP (Adenosine Triphosphate)

The universal energy currency within cells, structured as a phosphorylated nucleotide consisting of adenine, ribose, and three phosphate groups.

Substrate-linked phosphorylation

A process where $ATP$ is produced by direct synthesis in a reaction where energy in chemical bonds is reorganized, occurring in glycolysis and the Krebs cycle.

Chemiosmotic phosphorylation

Synthesis of $ATP$ resulting from a proton gradient established by pumping protons across a membrane in mitochondria and chloroplasts.

ATP synthetase

A membrane protein enzyme that spins as protons diffuse through it down an electrochemical gradient, accepting $ADP$ and inorganic phosphate to form $ATP$.

Palisade mesophyll

Leaf tissue containing many chloroplasts, where cells are cylindrical and arranged at right angles to the epidermis to maximize light absorption.

Stroma

The colourless, protein-rich region surrounding the grana in chloroplasts where the light-independent stage of photosynthesis occurs.

Thylakoid

Membranous sacs stacked within chloroplasts that contain electron carriers, proton pumps, and photosystems for the light-dependent stage.

Photolysis

The splitting of water by an enzyme in the thylakoid membrane to provide protons ($H^+$), electrons ($e^-$), and oxygen ($O_2$).

Calvin cycle

A series of reactions in the stroma involving the fixation of carbon dioxide, reduction, and resynthesis of the acceptor molecule $RuBP$.

Absorption spectrum

A graph showing the pattern of different wavelengths of light absorbed by a specific pigment, such as chlorophyll a or b.

Action spectrum

A graph showing the rate at which photosynthesis occurs across the visual electromagnetic spectrum ($400$ to $700\,nm$).

Rubisco

Ribulose bisphosphate carboxylase/oxygenase; the enzyme that catalyzes the initial carboxylation reaction in the Calvin cycle.

Triose phosphate (TP)

A three-carbon ($3C$) intermediate sugar produced in the Calvin cycle that can be converted into starch, sucrose, lipids, or amino acids.

Limiting factor

Any environmental factor, such as light intensity, temperature, or $CO_2$ concentration, that prevents the rate of a process from increasing further.

Aerobic respiration

The stepwise breakdown of organic molecules requiring oxygen to produce carbon dioxide, water, and managed packets of energy in $ATP$.

Glycolysis

The metabolic pathway occurring in the cytosol that converts glucose into pyruvate, yielding a net gain of $2\,ATP$ and reduced $NAD$.

Mitochondrial matrix

The site of the link reaction and Krebs cycle, containing DNA loops, $70S$ ribosomes, and various metabolic enzymes.

Decarboxylation

The metabolic removal of a carboxyl group from a compound, resulting in the formation of carbon dioxide ($CO_2$).

Dehydrogenation

The removal of hydrogen atoms from a substrate, usually involving the reduction of coenzymes like $NAD$ or $FAD$.

Oxygen debt

Extra oxygen uptake during recovery from exercise used to reload hemoglobin, oxidise lactate in the liver, and resynthesize $ATP$.

Ecosystem

A self-contained community of organisms and all the physical features influencing it and the interactions between them.

Ecological niche

The specific role of a species within a community, including its feeding position and interactions with the environment.

Keystone species

An organism, such as the sea otter or long-black-spine sea urchin, that plays a pivotal role in maintaining the structure and biodiversity of its ecosystem.

Nitrification

The two-step conversion of ammonia or ammonium ions into nitrite by Nitrosomonas, and then into nitrate by Nitrobacter.

Translocation

The movement of phloem sap containing assimilates, such as sucrose and amino acids, from source tissues to sink tissues.

Xylem

Plant tissue consisting of dead, lignified vessel elements that transport water and ions in the transpiration stream.

Casparian strip

An impermeable layer of suberin in the endodermal cell walls of roots that forces water and ions from the apoplast into the symplast pathway.

Homeostasis

The maintenance of a near-constant internal environment, such as blood glucose levels or core body temperature, despite external changes.

Negative feedback

A control mechanism that responds to a deviation from a set point by triggering corrective actions to return the factor to its ideal level.

Nephron

The functional unit of the kidney, consisting of a Bowman's capsule, convoluted tubules, and a loop of Henle.

Antidiuretic hormone (ADH)

A peptide hormone that increases the water potential of the blood by stimulating the insertion of aquaporins into the collecting duct membranes.

Action potential

A reversal in potential difference across a neurone membrane from about $-70\,mV$ to $+30\,to\,+40\,mV$, propagating a nerve impulse.

Dengue fever

An infectious disease caused by the $DENV$ virus and transmitted by the vector Aedes aegypti, characterized by high fever and severe body aches.

Metastasis

The spreading of malignant cancer cells from a primary tumour to other parts of the body via lymphatic vessels or the bloodstream.

Atherosclerosis

A chronic condition where fatty plaques (atheroma) accumulate within the walls of arteries, narrowing the lumen and increasing thrombosis risk.

Drug tolerance

A state where the body increases its metabolism of a drug or reduces receptor response, requiring higher doses to achieve original effects.