Do you often find that you get lost in the sea of HSC Biology Terms and Definitions?
Do your eyes glaze over when your teacher starts talking in ‘Biologese’ because you don’t know what any of the words mean?
Fear no more!
I hereby seek to dispel the mystery of Biologese with the following HSC Biology Terms and Definitions complete with useful examples!
Let’s dive into these biology terms!
Heredity
Genetic Change
Infectious Disease
Non-Infectious Disease and Disorders
60+ HSC Biology Terms and Definitions
Heredity
Term | Definition | Example and related concepts |
---|---|---|
Sexual reproduction | Genetic information comes from two sexes, and gametes must meet and fuse | For humans, the egg and sperm will meet. For flowers, the ovule and the pollen will meet. |
Asexual reproduction | Doesn’t require an egg and sperm (gametes) to meet, and usually comes from one organism | Bacteria can split from a single cell in a process called binary fission |
Gamete | Gametes are cells which can give rise to a new organism when they meet with a gamete of the opposite gender. | Gametes usually have a haploid chromosomes (half the number of chromosomes in an adult). |
External fertilisation | Egg and sperm meet outside the female body | Fish and frogs can release their eggs and sperm outside their body. Water assists in keeping them moist. |
Internal fertilisation | Egg and sperm meet inside the female body | Seen in humans, dogs and cats |
Binary fission | Type of asexual reproduction where bacteria ‘split’ in half, each half becomes a new daughter cell | When comparing the life cycle between prokaryotes and eukaryotes, there are similarities that can be drawn. Both replicate their DNA, and both increase the size of the cell to create two daughter cells except this occurs in the organism level for bacteria, and the cell level for humans. |
Budding | Type of yeast asexual reproduction where cells grow bigger until a little ‘bud’ forms on the mother cell. This bud grows bigger until it is big enough to break off. | Great demonstration of budding is the immortal hydra |
Mitosis | Cell division where daughter cells have the same number of chromosomes | Human somatic cells replicate by mitosis. The new daughter cells are identical to the mother cell. |
Meiosis | The process by which cells are replicated but it is different from mitosis because 1 parent cell gives rise to 4 daughter cells, which are different because of crossing over | Haploid gametes are produced from meiosis. It is important that the daughter cells aren’t identical to the mother cells. |
DNA replication | Making new copies of DNA so new cells can have a copy | DNA replication is a semi-conservative process which means that the two new DNA molecules that are made contains one strand of the original DNA |
Transcription | The process of copying information encoded in DNA into a ‘photocopy’ or RNA so the ribosome can read it | DNA is hard to read because it is so long and the structure is different. mRNA is a direct copy of the sequences in DNA, making it easier to use the information encoded in the genome |
Translation | Ribosome ‘reading’ the mRNA which tells it to recruit certain amino acids. Results in a polypeptide chain | tRNAs carry amino acids to the growing polypeptide chain |
Polypeptides | Polypeptides are short proteins made up of chains of amino acids | Polypeptides are usually smaller than proteins but larger than peptides and amino acids |
Chromosome | A chromosome is a package of DNA, which is a long DNA molecule that is coiled tightly for easy storage and movement | Humans have 46 chromosomes (26 pairs) |
Gene | A gene codes for a particular characteristic. A gene is a section of our DNA molecule | The gene for eye colour |
Allele | Allele is a form of a gene. For each gene, we have two alleles – one from mum and one from dad | A blue eye allele and a brown eye allele |
Phenotype | This is the physical characteristic of a genotype | Brown eyes are coded for by genotype ‘Aa’ |
Genotype | A genotype is the genetic code for a characteristic | Aa |
Homozygous genotypes | Genotypes where the two alleles are the same | AA or aa |
Heterozygous genotypes | Genotypes where the two alleles are different | Aa or Bb |
Simple dominance | Where one allele is completely dominant over the other (the recessive allele) | Where greenness is dominant over yellowness (of Mendel’s peas) |
Monohybrid cross | A Medelian cross where the two individuals have the same genotype | Cross of AA and AA or Aa and Aa |
Co-dominance | Where two or more alleles have equal dominance (which gives rise to a third outcome) | Snapdragons experiment, where a red one and a white one will cross to form a pink one. Red and white are co-dominant. |
Sex-linked genes | A common genetic variation that occurs in >1% of the population | >1% of people have a C T nucleotide mutation in a specific part of their DNA |
Single nucleotide polymorphism (SNP) | A common genetic variation that occurs in >1% of the population | >1% of people have a C T nucleotide mutation in a specific part of their DNA |
DNA sequencing | Finding out what the sequence of DNA is | Illumina technology is commonly used at and can find the sequence (CTTAGACCGA…) of almost all of the 3 billion base pairs that you have |
Genetic Change
Term | Definition | Example and related concepts |
---|---|---|
Mutagen | Anything causing mutations | Cigarette smoke |
Mutation | A change in DNA sequence | Point mutations are one nucleotide differences in a gene (CTAGTA CTTGTA) |
Genetic flow/gene mutation | Introducing genes of one population into another by breeding between two populations | A bee carrying the pollen from one population of flowers to another can be considered genetic flow |
Genetic diversity | Variation in a genetic pool for a particular characteristic | Genetic diversity is the reason why some people have black hair, others have brown hair, and others still can have blonde or red hair. |
Biotechnology | Using biology for industry | We can use massive cultures of bacteria to make drugs at the industrial scale |
Artificial insemination | Taking semen from a male animal and inserting it into a female uterus | Farmers pick which cows mate to ensure that the cow with the best characteristics mate and to prevent inbreeding |
Artificial pollination | Taking pollen or stamen from one plant into the pistil of another | The characteristics of flowers can be mixed |
Cloning | Creating a genetically identical copy of an organism | Whole organism cloning of dolly the sheep |
Transgenic organisms | Species which are the result of genetic modification | ‘Anti-freeze strawberries’ |
Infectious Disease
Term | Definition | Example and related concepts |
---|---|---|
Pathogen | A foreign body that can cause disease | Chickenpox |
Antigen | Molecules made of protein which are on the surface of cells that trigger the immune response when they detect infectious pathogens | The Rhesus antigen causes our blood type to be + or – |
Antibody | Made by plasma cells which specifically target a pathogen by binding to it | Starts getting released after the innate immune system can’t defeat the infection |
Epidemic | An infectious disease spreading across a wide range | AIDS epidemic |
Innate immune system | Made up of neutrophils, macrophages and other cells to attack any non-specific response | Any bacteria or virus entering gets attacked by the same molecules. E.g. regardless if it is S. aureus or E. coli, they get attacked by cytokines and other molecules |
Adaptive immune system | Made up of T cells and B cells and attack a specific pathogen | T cells and B cells prepare chemicals and molecules to specifically attack either S. aureus or E. coli |
Cytokines | Proteins that immune cells use to communicate with each other | Cells can release growth factors (GFs), interferons (IFs) and interleukins (ILs) |
Cell differentiation | How cells become specialised for their different functions. They all start off exactly the same | White blood cells specialise from stem cells |
Quarantine | Isolation after coming from another country to make sure they don’t spread potential diseases | Waiting to see if plants/animals have introduced infectious diseases prevents introducing the disease to an unimmune public |
Passive immunity | Injection of someone else’s antibodies | If you wait for your body to respond to neutralise snake bites, it’ll be too late. We use another animals’ antibodies and inject it into the affected person. These antibodies will act to neutralise the bite without needing an immune reaction |
Active immunity | Making your own antibodies | After a vaccine, your body responds by making antibodies against the infectious agent |
Non-Infectious Disease and Disorders
Term | Definition | Example and related concepts |
---|---|---|
Homeostasis | A process involving feedback networks (positive and negative) that means that organisms (like humans) can adapt to changes in their environment | When it is warm, mammals have mechanisms like sweating which allow us to adapt to the environment. If we did not have these mechanisms, our enzymes would denature! |
Enzymes | A protein that is responsible for lowering the activation energy of a reaction, making it occur faster | Bromalain is an enzyme found in pineapple and kiwi fruit. Lock and key model of substrate specificity for enzymes. Enzymes will become denatured if the temperature or pH changes outside of its optimal range. |
Substrates | Molecules part of a chemical reaction which react together to form the products | Substrates are the molecules which go into enzymes |
Optimal | Best for efficiency of a reaction | Optimal temperature of most human chemical reactions and their enzymes is around 37 degrees Celsius (this is our human body temperature is around this range) |
Endotherm organisms | Organisms which control their own body temperature, independently of the outside environment | ‘Warm blooded’ animals, such as humans and other mammals |
Ectotherm | Organisms which do not control their own body temperature, and rely on the outside environment | ‘Cold blooded’ animals, such as lizards and other reptiles |
Adaptive advantage | An advantage of a particular characteristic which helps the organism to adapt to the environment, according to the theory of evolution by natural selection | An adaptive advantage for a frog living in a green forest is that it has green skin which allows it to camouflage, and thus survive and pass on its genetic characteristics to its offspring |
Hormones | Chemicals which are used to control organs in the body | Anti-diuretic hormone (ADH) can tell the kidney to reabsorb more water, and so the need to urinate is decreased |
Disease | Disturbance in normal structure and function caused by something outside the body | Can be caused by improper diet or radiation exposure |
Disorder | Disturbance in normal body structure and function caused by something inside the body | Can be caused by genes, birth defects |
Cancer | Uncontrolled growth of cells | Stomach cancer is when stomach cells keep dividing and don’t stop |
Incidence | How many new cases of this disease in x time? | Estimated 14,320 new melanoma cases diagnosed in 2018 |
Prevalence | How many people have had this disease in x time? | At the end of 2013, 53,215 people were living with melanoma |
Mortality | Number of deaths in a given time or location | Skin cancer mortality in Australia is estimated to be 3.9% of all deaths in 2018 |
Epidemiology | The study of how a disease occurs and spreads and where it is most prevalent | Epidemiology allows us to understand why a disease starts and spreads and how to tackle it |
Genetic engineering | Changing the characteristics of an organism by changing its genes | Mice that glow due to the insertion of a gene that makes fireflies glow |
Ready to take on some questions? Check out our Master List of 2009-2022 HSC Biology Past Papers for practise!
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Gia-Yen Luong has been an Art of Smart coach for 3 years, coaching a range of subjects including HSC English, Legal Studies, Biology, Chemistry and General Maths. She is in her final year of a mega double degree in Law/Science (Neuroscience). She graduated high school with an ATAR of 99.9 and spends most of her time trying to convince people that it’s wholly possible to get such a mark while still having a normal life during Year 12. She enjoys reading, podcasts and Clash of Clans. In effect, she is a true nerd.