Year 10 - Biology

All Topics Covered during Year 10 Biology

Chromosomes

Thread-like structures in the nucleus. Composed of DNA and proteins; contains the genetic information in the form of genes

Complementary base pairs

A pair of bases that can join to make the rungs of the DNA ladder—adenine and thymine, guanine and cytosine

Deoxyribonucleic acid (DNA)

A nucleic acid with deoxyribose sugar and phosphate as the backbone; the molecule that determines the genetic characteristics of most living things

Deoxyribose sugar

One of the parts that make up a nucleotide

Gene

A section of DNA that carries the genetic code for a particular characteristic

Nitrogen-rich base

Part of a nucleotide; the four types are adenine (A), guanine (G), cytosine (C) and thymine (T)

Nucleotides

The building blocks of DNA

Phosphate group

One of the parts that make up a nucleotide

Autosomes

All the chromosomes in a cell other than the sex chromosomes

Centromere

The point on a chromosome where the two chromatids are joined together

Chromatid

One of the strands of a chromosome following replication

Diploid number

The number of chromosomes in body cells; two sets or $2N$

Haploid number

The number of chromosomes in gametes; one set or $N$

Homologous chromosomes

Chromosomes with genes for particular characteristics at the same location

Meiosis

The type of cell division that produces gametes with half the number of chromosomes of the parent cell

Mitosis

The type of cell division that produces two daughter cells identical to the parent cell

Replication

The process of making copies of DNA

Sex chromosomes

The chromosomes that determine the sex of an individual; in humans they are the X and Y chromosomes

Alleles

Different forms of the same gene

Dominant

The characteristic that is expressed in the homozygous condition

Genotype

Genetic information carried by an individual

Heterozygous

Having two different alleles on homologous chromosomes

Homozygous

Having two identical alleles on homologous chromosomes

Incomplete dominance

Where the appearance of a heterozygous individual results from a 'blending' of the two alleles because one allele is not completely dominant over the other

Mutation

A mistake that happens as DNA is copied, causing a change to the base sequence

Phenotype

Observable characteristics of the individual; the way the genotype is expressed

Pure breeding

Where all individuals have the same genetic information for a characteristic generation after generation

Recessive

The characteristic that remains hidden in the homozygous condition

Sex-linked genes

Genes present on the sex chromosomes

Differentiate

Become different from others

Gene splicing

The process used to add a gene into or remove genes from DNA

Gene therapy

The process of replacing a defective gene with a normal gene

Genetically modified

Having the genes changed

Genome

The genetic information carried by a haploid set of chromosomes

Ribonucleic acid (RNA)

A single-stranded nucleic acid containing ribose sugar and uracil that functions in protein synthesis.

Transcription

The process of copying a specific segment of DNA into messenger RNA inside the nucleus.

Translation

The process where ribosomes decode mRNA to assemble amino acids into a polypeptide chain.

Uracil

The pyrimidine base present in RNA that pairs complementarily with adenine in place of thymine.

Codon

A three-nucleotide sequence in mRNA that specifies a single amino acid or a termination signal.

Prophase

The first stage of mitosis where chromatin condenses into visible chromosomes and the nuclear envelope begins to break down.

Metaphase

The stage of mitosis where chromosomes align along the equator of the cell and attach to spindle fibres.

Anaphase

The stage of mitosis where sister chromatids separate at the centromere and migrate toward opposite poles.

Telophase

The final phase of mitosis where nuclear membranes reform around separated groups of chromosomes.

Cytokinesis

The physical division of the cytoplasm and cell membrane that separates the parent cell into two daughter cells.

Spindle fibres

Microtubule structures that extend from centrioles to attach to centromeres and pull chromatids apart.

Crossing over

The exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis.

Punnett square

A grid diagram used by geneticists to predict the possible genotypic and phenotypic outcomes of a genetic cross.

Carrier

An individual heterozygous for a recessive condition who displays a normal phenotype but can transmit the allele to offspring.

Species

A biological classification unit consisting of organisms that can interbreed under natural conditions to produce fertile offspring.

Hybrid

An organism produced from the interbreeding of two different species or distinct varieties.

Taxonomy

The scientific discipline of naming, defining, and classifying organisms based on shared characteristics.

Linnaean classification

A hierarchical system that categorises organisms into kingdom, phylum, class, order, family, genus, and species.

Natural selection

The evolutionary mechanism where environmental factors favour the survival and reproductive success of individuals with advantageous phenotypes.

Selective agent

An environmental factor, either biotic or abiotic, that acts on a population during natural selection.

Selection pressure

The effect or intensity with which a selective agent drives changes in traits within a population.

Artificial selection

The selective breeding of plants or animals by humans to produce offspring with specific desirable characteristics.

Cross-breeding

The mating of two individuals with different desirable features to combine those traits in their offspring.

Inbreeding

Selective breeding between closely related individuals, often increasing the expression of deleterious recessive traits.

Speciation

The evolutionary process by which a single population splits and diverges into two or more distinct species.

Adaptive radiation

The rapid divergence of an evolutionary lineage into many new forms that occupy different ecological niches.

Transitional form

A fossil showing intermediate features between an ancestral group and its derived descendant organisms.

Analogous structures

Anatomical features in different organisms that perform the same function but evolved independently without a common ancestor.

Vestigial structures

Anatomical structures that have lost their original biological function over evolutionary time.

Biogeography

The study of the geographic distribution of species across Earth throughout geological time.

Comparative embryology

The scientific analysis and comparison of embryonic development across different animal species to show common ancestry.

DNA hybridisation

A molecular technique that combines single strands from different species to evaluate relatedness through base pairing.

Antibiotic resistance

The inherited capacity of bacterial populations to survive exposure to chemicals designed to destroy them.

Homologous structures

Anatomical features in different species that share a common internal structure and ancestral origin, despite serving different functions.

Pentadactyl limb

A five-digit skeletal limb structure found across tetrapod vertebrates that illustrates common ancestry.

Comparative anatomy

The scientific study of similarities and differences in the physical body structures of distinct species.

Interphase

The preparatory stage in the cell cycle prior to division where the cell synthesises proteins, grows, and replicates its chromosomes.

Ribose sugar

The five-carbon pentose sugar that forms part of the repeating sugar-phosphate backbone in RNA molecules.

Messenger RNA (mRNA)

A linear single-stranded transcript produced from DNA that transports protein-building instructions to the ribosomes.

Transfer RNA (tRNA)

A folded RNA molecule that brings specific amino acids to the ribosome during translation by pairing its anticodon with an mRNA codon.

Anticodon

A specific triplet sequence of nucleotides on a tRNA molecule complementary to a corresponding triplet on an mRNA strand.

RNA polymerase

The primary enzyme that binds to DNA to synthesise a complementary strand of RNA during transcription.

Centrioles

Paired cylindrical structures in animal cells that migrate to opposite poles to organize the spindle apparatus during division.

Cleavage furrow

A shallow constriction in the cell membrane that pinches inward to divide the cytoplasm during animal cell cytokinesis.

Cell plate

A temporary structure formed across the dividing plane of plant cells that develops into a new cell wall.

Synapsis

The physical pairing and alignment of homologous chromosomes side-by-side during prophase I of meiosis.

Independent assortment

The random orientation and segregation of maternal and paternal homologous chromosome pairs during metaphase I of meiosis.

Biodiversity

The variety and abundance of different species living on Earth or within a particular ecosystem.

Sexual selection

A mode of natural selection where mating preferences and mate choice drive the evolution of specific phenotypic traits.

Palaeontology

The scientific study of prehistoric life and geological time through the discovery and analysis of fossils.

Fossil record

The total chronological accumulation of preserved traces and remains of past organisms found within Earth's geological strata.

Common ancestor

An ancestral organism or taxonomic group from which two or more evolutionary lineages have directly descended.

Branchial arches

Pharyngeal anatomical structures in early vertebrate embryos that develop into diverse adult organs such as gills, jaws, or inner ear bones.

Geographical isolation

The physical separation of populations by geographic barriers like oceans or mountains, preventing interbreeding and gene flow.

Hybrid vigour

The increased vitality, growth rate, or health displayed by offspring produced from crossing different varieties or species.

Niche

The distinct ecological role, habitat, and resource space occupied by an organism within a community.

Biotic factor

A living component of an ecosystem, such as a competitor, predator, or disease agent, that acts as a selective agent.

Abiotic factor

A non-living physical or environmental influence, such as temperature, rainfall, or sunlight, that exerts selection pressure.

Superbugs

Bacterial strains that have developed resistance to multiple classes of commonly used antibiotics.

Evolution

The change in the inherited characteristics of a biological population over many generations, leading to the formation of new species.

Variation

The structural, functional, or traits-based differences between individuals of a population caused by different genes.

Gene flow

The transfer and exchange of alleles between interbreeding populations, which is prevented by isolating barriers.

Generation

The time span between the birth of an individual organism and when that individual produces its own offspring.

Morphology

The physical form, structure, and external anatomical features of an organism used in biological classification.

Ribosomal RNA (rRNA)

A structural nucleic acid molecule that twists and forms loops to combine with proteins to construct ribosomes.

Somatic cells

All non-reproductive body cells containing a full diploid ($2N$) set of chromosomes that divide via mitosis.