UAE TLS Biology Test flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Fluid mosaic model

Model describing the cell membrane as a phospholipid bilayer with embedded proteins, cholesterol and glycoproteins that move laterally, giving the membrane a flexible, mosaic-like structure.

Competitive inhibitor

A molecule that binds to an enzyme's active site and competes with the substrate, increasing the substrate concentration needed to reach a given reaction rate; it raises Km but not Vmax.

Osmosis

The net movement of water molecules across a partially permeable membrane from a region of lower solute concentration to a region of higher solute concentration, down a water potential gradient.

Law of segregation

Mendel's principle that the two alleles of a gene separate during meiosis so that each gamete receives only one allele, with pairs restored at fertilisation.

Codominance

A pattern in which both alleles in a heterozygote are fully expressed in the phenotype, as in AB blood type, rather than blending to produce an intermediate trait.

Frameshift mutation

An insertion or deletion of a number of nucleotides not divisible by three, which shifts the reading frame and alters every subsequent codon, usually producing a non-functional protein.

Sinoatrial node

The sinoatrial node is the heart's natural pacemaker, located in the right atrium; it generates electrical impulses that set the resting heart rate.

Cardiac output

The volume of blood pumped by one ventricle per minute, calculated as heart rate multiplied by stroke volume; a typical resting value is about five litres per minute.

Antidiuretic hormone

Antidiuretic hormone, released by the pituitary gland, increases water reabsorption in the kidney collecting ducts, producing more concentrated urine and reducing water loss.

Hardy-Weinberg equilibrium

The condition in which allele and genotype frequencies in a population remain constant across generations, requiring no mutation, no migration, random mating, no selection and a large population.

Homologous structures

Body parts in different species that share a common evolutionary origin and similar underlying anatomy, such as the forelimbs of humans, whales and bats, indicating divergent evolution.

Allopatric speciation

The formation of new species when a population is divided by a geographic barrier, preventing gene flow and allowing independent mutation, genetic drift and selection to diverge the groups.

Carrying capacity

The maximum population size of a species that an ecosystem can sustain indefinitely, given the available food, water, space and other limiting resources; symbol K.

Trophic level

A feeding position in a food chain, such as producer, primary consumer or secondary consumer; only about ten per cent of energy passes to the next level.

Nitrification

The conversion of ammonium ions in soil into nitrites and then nitrates by nitrifying bacteria, making nitrogen available for uptake by plant roots.

Transpiration

The loss of water vapour from leaves through stomata, creating a pulling force that draws water and dissolved minerals up the xylem from the roots.

Calvin cycle

The light-independent stage of photosynthesis in the stroma, where carbon dioxide is fixed by RuBP and reduced using ATP and NADPH to form triose phosphate and regenerate RuBP.

Auxin

A plant hormone produced at shoot tips that promotes cell elongation, controls phototropism and geotropism, and maintains apical dominance by suppressing lateral bud growth.

Polymerase chain reaction

A technique that amplifies a specific DNA sequence through repeated cycles of denaturation, primer annealing and extension by Taq polymerase, doubling the target DNA each cycle.

Restriction enzyme

An enzyme that recognises a specific short palindromic DNA sequence and cuts the sugar-phosphate backbone, often producing sticky ends used to insert genes into plasmids.

Gel electrophoresis

A method that separates DNA fragments by size using an electric field; negatively charged DNA moves toward the positive electrode, with smaller fragments travelling farther through the gel.

Independent variable

The factor deliberately changed or manipulated by the researcher in an experiment, whose effect on the dependent variable is being measured.

Control group

The group in an experiment that does not receive the treatment and is used as a baseline for comparison, helping to show that changes are due to the independent variable.

Reliability

The extent to which repeated measurements or experiments produce consistent results; it is improved by using larger samples, repeat trials and standardised procedures.

Autoclave

A sealed chamber that uses steam at about 121 degrees Celsius and 15 psi for 15 minutes to sterilise equipment and destroy microorganisms, including resistant bacterial spores.

Safety Data Sheet

A standard document supplied with a chemical that lists its hazards, safe handling procedures, first-aid measures, storage requirements and disposal methods.

Sharps container

A puncture-resistant, clearly labelled bin used to dispose of broken glass, needles and other sharp items that could injure people and transmit infection.

Standard deviation

A measure of the spread of data around the mean; a small value indicates values clustered close to the mean, while a large value indicates greater variability.

Chi-square test

A statistical test comparing observed and expected frequencies using the formula sum of (O minus E) squared divided by E, to judge whether differences are statistically significant.

Correlation coefficient

A value between minus one and plus one describing the strength and direction of a linear relationship between two variables; zero indicates no linear relationship.

Formative assessment

Ongoing assessment during learning, such as questioning, quizzes or feedback, used to identify gaps and adjust teaching rather than to assign a final grade.

Constructive alignment

The principle that intended learning outcomes, teaching and learning activities, and assessment tasks should all match each other so that assessment genuinely tests the stated outcomes.