Biology HL - Life, Cells, and Prebiotic Chemistry

Vocabulary practice flashcards generated from Higher Level Biology notes covering water polarity, homeostasis, metabolism, prebiotic conditions, cell origins, prokaryotic and eukaryotic structures, and microbial diversity.

Chemical Reaction

A process where substances are changed into different substances.

Metabolic Reaction

A chemical reaction that happens inside a living organism to keep it alive.

Polarity of Water

The structural property of a water molecule having a slightly negative charge on the oxygen atom ($\delta^-$) and slightly positive charges on the hydrogen atoms ($\delta^+$).

Homeostasis

A body's automatic process to keep its internal state stable (such as temperature and water levels) so that cells and organs can function properly.

Receptors

Sensory components in the body that find or detect changes in the body's internal state.

Control Center

The organ or system (such as the brain) that processes information from receptors and formulates plans to match internal changes.

Effectors

Muscles or glands that execute responses to restore internal body conditions to their original set point.

Negative Feedback

A homeostatic mechanism in which the body counteracts a change in order to return to its original set point.

Positive Feedback

A physiological mechanism where the body pushes a change further away from the set point to complete a specific task, such as blood clotting.

Catabolic Reactions

Metabolic processes that break down larger, complex molecules into smaller molecules, releasing energy in the process.

Anabolic Reactions

Metabolic processes that synthesize larger molecules from smaller precursor molecules using energy.

Autotrophs

Organisms that synthesize their own organic food from simple substances using processes like photosynthesis.

Heterotrophs

Organisms that cannot make their own organic food and must obtain nutrients by consuming other organisms or organic matter.

Sessile Organisms

Organisms that remain fixed in one place throughout their life cycle.

Motile Organisms

Organisms capable of independent movement from one place to another.

Excretion

The biological process by which metabolic waste matter is eliminated from an organism.

Haploid Cells

Reproductive cells, such as sperm cells and ova, that contain half the standard number of chromosomes.

Cell Theory

The biological principle stating that all living things are composed of cells, cells are the basic units of life, and all cells arise from pre-existing cells.

Spontaneous Generation

An obsolete belief prior to cell theory asserting that living organisms could arise directly from non-living matter.

Cultured Cells

Cells removed from a multicellular body and grown artificially in a laboratory environment where they can survive and divide.

Compartmentalization

A necessary step in cell evolution where a outer membrane forms to enclose internal cellular contents and reactions.

Haldane's Idea

The hypothesis proposing that early Earth oceans formed a 'Hot Dilute Soup' containing simple chemicals that reacted under UV light to produce organic compounds.

Miller-Urey Experiment

An experiment simulating early Earth's atmosphere and water cycle using electrical sparks and gases (methane, hydrogen, ammonia) to demonstrate abiotic synthesis of carbon compounds.

Vesicle

A small fluid-filled structure bounded by a phospholipid membrane that can form spontaneously in aquatic environments.

Nucleoid

The region within a prokaryotic cell where the circular genetic material (DNA) is located.

Plasmids

Small, autonomous circular DNA molecules present in prokaryotic cells that can replicate independently.

Pili

Hair-like extensions on prokaryotic cell surfaces that facilitate attachment to external surfaces and horizontal DNA transfer.

Capsule

An outer protective layer surrounding certain prokaryotic cells that shields them from extreme environmental conditions.

RNA World Hypothesis

The hypothesis that early life relied on RNA molecules as both the primary carrier of genetic information and the catalytic machinery.

Ribozymes

RNA molecules with enzymatic capabilities that allow them to catalyze specific biochemical reactions.

Lysosome

A membrane-bound organelle containing digestive enzymes used to break down cellular debris and waste materials.

Light Micrograph

A two-dimensional image captured via a light microscope displaying macroscopic cell architecture and cell walls.

Electron Micrograph

A high-resolution image taken using an electron microscope that reveals intricate internal organelle ultrastructures.

Obligate Aerobes

Organisms that require a constant supply of oxygen to perform cellular respiration and generate ATP.

Obligate Anaerobes

Organisms that are poisoned or killed by oxygen and only survive in strictly anoxic environments.

Facultative Anaerobes

Organisms capable of switching between aerobic respiration and anaerobic metabolic pathways depending on oxygen availability.

Winogradsky Column

A closed mud and water microcosm exposed to sunlight used to study microbial stratification according to varying chemical and oxygen gradients.

Archaea

A domain of single-celled prokaryotic organisms, frequently found in extreme environments, possessing unique cell membrane structures distinct from Bacteria.

Chemoautotrophs

Organisms that synthesize organic compounds using chemical energy derived from inorganic oxidation reactions rather than light.