Mind the Gap: Life Sciences CAPS Grade 12 - Vocabulary Flashcards

A set of vocabulary flashcards covering core terms and definitions from the Mind the Gap Life Sciences CAPS Grade 12 syllabus as presented in the notes.

Nucleotide

The basic building block of nucleic acids (DNA and RNA), consisting of a sugar, a phosphate group, and a nitrogenous base.

DNA

Deoxyribonucleic acid; a double-stranded molecule that stores genetic information in the nucleus, with bases A-T and C-G.

RNA

Ribonucleic acid; usually single-stranded, contains ribose sugar, and uses bases A, U, C, G.

Adenine pairing (DNA)

Adenine pairs with thymine (A–T) via two hydrogen bonds in DNA.

Adenine pairing (RNA)

Adenine pairs with uracil (A–U) in RNA instead of thymine.

Thymine

A DNA nitrogenous base that pairs with adenine.

Cytosine

A DNA/RNA nitrogenous base that pairs with guanine.

Guanine

A DNA/RNA nitrogenous base that pairs with cytosine.

Uracil

An RNA nitrogenous base that pairs with adenine (replaces thymine in RNA).

DNA replication

The process by which the DNA molecule copies itself before cell division, producing two identical DNA molecules.

DNA profiling

A method of identifying individuals based on unique DNA fragment patterns.

Transcription

DNA is copied into messenger RNA (mRNA) in the nucleus.

Translation

mRNA is read by ribosomes to assemble amino acids into a protein; involves tRNA and rRNA.

Codon

A triplet of bases on mRNA that codes for a specific amino acid.

Anticodon

A triplet of bases on tRNA that pairs with a codon on mRNA.

mRNA

Messenger RNA; carries genetic information from DNA to the ribosome for protein synthesis.

tRNA

Transfer RNA; brings specific amino acids to the ribosome during translation.

Ribosome

Cell organelle where translation occurs; builds proteins from amino acids.

Protein synthesis

The process by which cells build proteins, including transcription and translation.

Meiosis

A type of cell division that produces four haploid gametes from a diploid cell, reducing chromosome number by half.

Diploid

Cells with two sets of chromosomes (2n).

Haploid

Cells with a single set of chromosomes (n); gametes are haploid.

Homologous chromosomes

Pairs of chromosomes that carry the same genes at the same loci but may have different alleles.

Chiasma

The site where crossing over occurs between homologous chromosomes during meiosis I.

Crossing over

Exchange of genetic material between homologous chromosomes, increasing genetic variation.

Non-disjunction

Failure of chromosome pairs to separate properly during meiosis, leading to abnormal chromosome numbers.

Zygote

The fertilized egg formed from the union of sperm and egg.

Gamete

A reproductive cell; sperm in males or ova in females.

Sperm

Male gamete; fertilizes the egg.

Ova (eggs)

Female gametes; fertilization by sperm forms a zygote.

Fertilisation

Union of sperm and egg resulting in a zygote.

Gestation

The period of development from fertilization to birth.

Placenta

Organ that develops during pregnancy to exchange nutrients and wastes between mother and fetus.

Endometrium

Inner lining of the uterus that thickens during the menstrual cycle to receive a fertilized egg.

Menstrual cycle

Hormone-regulated cycle of ovulation and uterine lining changes in females.

FSH (follicle-stimulating hormone)

Pituitary hormone that stimulates follicle development in the ovaries; involved in ovulation.

LH (luteinizing hormone)

Pituitary hormone that triggers ovulation and corpus luteum formation.

Estrogen

Female sex hormone that promotes egg development and endometrium thickening.

Progesterone

Hormone that maintains the endometrium and supports early pregnancy.

Testosterone

Male sex hormone produced by the testes; stimulates sperm development and secondary sexual characteristics.

Reproductive system (male)

Includes testes, epididymis, vas deferens, seminal vesicles, Cowper’s glands, prostate, scrotum, penis.

Reproductive system (female)

Includes ovaries, Fallopian tubes, uterus, cervix, vagina; uterus supports gestation.

Puberty

Period of sexual maturation with hormonal changes leading to reproductive capability.

Fertilisation vs gestation

Fertilisation is sperm-egg fusion; gestation is the period of development before birth.

Nervous system

Body system that processes and transmits information; includes brain and spinal cord.

Neuron

Nerve cell; types include sensory (afferent), motor (efferent), and interneurons.

Reflex arc

Neural pathway for a quick, involuntary response; receptor → neuron → interneuron → neuron → effector.

Brain parts (Cerebrum, Cerebellum, Medulla, Hypothalamus)

Cerebrum: thought and voluntary actions; Cerebellum: balance and coordination; Medulla: vital functions; Hypothalamus: homeostasis and temperature control.

Endocrine system

Glands that secrete hormones to regulate body activities.

Negative feedback

A control mechanism where the output reduces the original stimulus to restore balance.

Homeostasis

Maintenance of a constant internal environment (temperature, pH, glucose, etc.).

Glucose regulation

Control of blood glucose by insulin (lowers) and glucagon (raises).

Osmoregulation (ADH)

Regulation of water balance; antidiuretic hormone (ADH) controls kidney water reabsorption.

Temperature regulation

Process (involving hypothalamus, blood vessels, sweat glands) to maintain ~37°C.

Auxins

Plant hormones that regulate growth responses like phototropism and geotropism.

Phototropism

Growth toward or away from light in plants.

Geotropism

Growth response to gravity in plants.

Evolution

Change in the heritable characteristics of a population over generations; evidence includes fossils, genetics, and natural selection.

Natural selection

Process where advantageous traits increase in frequency due to environmental pressures.

Speciation

Formation of new species when populations become reproductively isolated.

Out of Africa hypothesis

Idea that modern humans originated in Africa and spread to other regions.

Biodiversity

The variety of life in all its forms, levels, and combinations on Earth.

Human impact on environment

Effects of human activities on ecosystems, including climate change, pollution, and resource use.

Waste management & recycling

Strategies to reduce, reuse, and recycle waste to protect the environment.