Year 10 Biology Term 3 Revision

Vocabulary flashcards covering key terms in Genetics, Cell Division, Evolution, and Immunology based on Year 10 Biology revision notes.

DNA

A nucleic acid molecule containing the genetic instructions for an organism's development and function, structured as a double helix composed of nucleotides.

Nucleotide

The repeating structural unit of DNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Gene

A specific section of DNA that contains the instructions to produce a protein.

Transcription

The process of copying a section of DNA into a complementary mRNA strand inside the nucleus.

Translation

The process where ribosomes read the mRNA sequence to assemble amino acids into a functional protein.

mRNA

Messenger RNA; a single-stranded RNA molecule transcribed from DNA that carries genetic information to the ribosome for protein synthesis.

Karyotype

An organized visual profile of an individual's complete set of chromosomes, used to check for numerical or structural chromosomal abnormalities.

Gene Mutation

A permanent change in the DNA base sequence of a gene, which can potentially alter the amino acid sequence and resulting protein.

Genotype

The genetic combination of alleles present in an organism for a specific trait, such as $Tt$ or $bb$.

Phenotype

The observable physical characteristics or traits of an organism determined by its genotype and environment.

Dominant Allele

An allele that expresses its characteristic in the phenotype even when only one copy is present in the genotype.

Recessive Allele

An allele whose trait is masked in the presence of a dominant allele and is only expressed when two copies are present in the genotype.

Dihybrid Cross

A genetic cross between two individuals to study the inheritance patterns of two unlinked traits simultaneously (e.g., $AaBb \times AaBb$).

Pedigree Chart

A diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism from one generation to the next.

Mitosis

A type of cell division resulting in two genetically identical daughter cells with the same number of chromosomes, used for growth and repair.

Meiosis

A type of cell division that produces four genetically unique daughter cells with half the original chromosome count, used for gamete production in sexual reproduction.

Crossing Over

The process during meiosis where homologous chromosomes exchange segments of genetic material, creating new allele combinations and genetic variation.

Natural Selection

The process through which organisms with traits better adapted to their environment tend to survive and reproduce more successfully, driving evolution.

Pathogen

A disease-causing agent, such as a bacterium, virus, fungus, or parasite.

First Line of Defence

Physical and chemical barriers, such as skin and mucous membranes, that prevent pathogens from entering the body.

Second Line of Defence

Non-specific immunity responses, such as inflammation and phagocytes, that act inside the body to fight off pathogens.

Third Line of Defence

Specific adaptive immunity that targets specific pathogens using specialized white blood cells, antibodies, and memory cells.

Antibiotics

Medicines used to treat bacterial infections by killing bacteria or inhibiting their growth, which have no effect on viruses.

Vaccines

Substances containing harmless or weakened parts of a pathogen (antigens) used to stimulate an immune response and build memory cells for long-term protection.