Angola 12th Grade Biology National Exam flashcards

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

Nucleus

Membrane-bound organelle in eukaryotic cells that contains the chromosomes and controls cell activities through gene expression.

Osmosis

Net movement of water across a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Mitochondrion

Organelle with a folded inner membrane where aerobic respiration occurs, producing most of the cell's ATP.

Enzyme active site

Specific region of an enzyme where the substrate binds; its shape determines specificity and is altered by high temperature or extreme pH.

Allele

One of two or more alternative forms of a gene occupying the same locus on homologous chromosomes.

Genotype

The genetic makeup of an organism, described by the alleles it carries for a gene or set of genes.

Phenotype

The observable characteristics of an organism, resulting from its genotype interacting with the environment.

Test cross

Crossing an individual showing a dominant phenotype with a homozygous recessive individual to determine whether the dominant individual is homozygous or heterozygous.

DNA replication

Semi-conservative process in which the double helix unwinds and each strand serves as a template for a new complementary strand.

Transcription

Process in which RNA polymerase builds a messenger RNA molecule using one DNA strand as a template.

Codon

Sequence of three mRNA bases that specifies one amino acid or a stop signal during translation.

Restriction enzyme

Enzyme that cuts DNA at a specific recognition sequence, producing fragments with sticky ends used in genetic engineering.

Polymerase chain reaction

Technique that amplifies DNA through repeated cycles of denaturation, primer annealing and extension by a heat-stable DNA polymerase.

Alveoli

Tiny air sacs in the lungs with thin walls and dense capillary networks where oxygen and carbon dioxide are exchanged.

Nephron

Functional unit of the kidney that filters blood and reabsorbs useful substances to form urine.

Insulin

Hormone secreted by the pancreas that lowers blood glucose by promoting uptake and storage of glucose.

Synapse

Junction between two neurons or a neuron and a muscle, where a neurotransmitter carries the signal across a small gap.

Fertilisation

Fusion of a haploid sperm and a haploid ovum to form a diploid zygote, normally occurring in the fallopian tube.

Placenta

Organ connecting mother and fetus that allows exchange of nutrients, oxygen and wastes and secretes hormones.

Ovulation

Release of a mature ovum from the ovary, typically around day 14 of a 28-day menstrual cycle.

Vaccination

Introduction of weakened or inactivated antigens to stimulate antibody production and immunological memory without causing disease.

Natural selection

Process in which individuals with heritable traits suited to their environment survive and reproduce more, increasing those traits in the population.

Homologous structures

Body parts in different species that share a common evolutionary origin but may differ in function, such as the forelimbs of vertebrates.

Species

Group of organisms that can interbreed to produce fertile offspring under natural conditions.

Binomial nomenclature

System of naming species with two Latin terms: the genus, capitalised, followed by the species name in lowercase.

Trophic level

Position an organism occupies in a food chain, such as producer, primary consumer or secondary consumer.

Carrying capacity

Maximum population size an environment can sustain indefinitely given available food, water, space and other resources.

Decomposer

Organism such as bacteria or fungi that breaks down dead organic matter, releasing nutrients back into the ecosystem.

Independent variable

Variable deliberately changed or manipulated by the researcher in an experiment to test its effect.

Control group

Group in an experiment that receives no treatment or a standard treatment and serves as a baseline for comparison.

Total magnification

Product of the eyepiece magnification and the objective lens magnification used when viewing a specimen.

Mean

Average of a set of values, calculated by summing all values and dividing by the number of values.