Unit 2 VCE Biology

Chromatid

Chromatid

one of two identical "sister" parts of a duplicated chromosome

homologous chromosomes

Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis.

Aneuploidy

the presence of an abnormal number of chromosomes in a cell

Monosomy

Chromosomal abnormality consisting of the absence of one chromosome from the normal diploid number

Trisomy

a condition in which an extra copy of a chromosome is present in the cell nuclei, causing developmental abnormalities.

Meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Zygote

a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

n chromosomes

haploid

2n+1

trisomy

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

independent assortment

the random distribution of the pairs of genes on different chromosomes to the gametes

Homozygous

Having two identical alleles for a particular gene

Heterozygous

having two different alleles for a particular gene

recessive allele

An allele that is masked when a dominant allele is present

Carrier

A person whose genotype includes a gene that is not expressed in the phenotype.

incomplete dominance

A pattern of inheritance in which two alleles, inherited from the parents, are neither dominant nor recessive. The resulting offspring have a phenotype that is a blending of the parental traits.

sex-linked gene

gene located on a sex chromosome

test cross

the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

gene pool

All the genes, including all the different alleles for each gene, that are present in a population at any one time

genetic diversity

a measure of the genetic variation among individuals in a population

sexual reprodcution

A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.

Budding

Asexual reproduction in which a part of the parent organism pinches off and forms a new organism

Fragmentation

A means of asexual reproduction whereby a single parent breaks into parts that regenerate into whole new individuals.

vegetative propagation

A form of asexual reproduction in which plants produce genetically identical offshoots (clones) of themselves, which then develop into independent plants.

parthenogenesis

Asexual reproduction in which females produce offspring from unfertilized eggs.

somatic cell nuclear transfer

a cloning technique that involves substituting genetic material from an adult's cell for the nucleus of an egg

embryo splitting

a form of cloning that is accomplished by dividing a growing embryo into equal parts using a surgical procedure performed with the aid of a microscope

plant cuttings

in plant cloning, a leaf and stem are cut off a plane and then dipped in hormone powder to encourage rooting, and a new plant grows

plant grafting

the attachment of two individual plant stems together

Abiotic

Non-living

structural adaptation

a physical feature of an organism's body having a specific function that contributes to the survival of the organism

physiological adaptation

a physical or chemical event that occurs within the body of an organism and enables survival

Ecosystem

A community of organisms and their abiotic environment

population size

the total number of individuals within a defined area at a given time

population density

Number of individuals per unit area

population distribution

how population is spread out in an area

carrying capacity

the largest population that an environment can support at any given time

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

Amensalism

a relationship between organisms of two different species in which one is unaffected and the other is negatively impacted by the association

Parasitism

A relationship between two organisms of different species where one benefits and the other is harmed

competition

A common demand by two or more organisms upon a limited supply of a resource; for example, food, water, light, space, mates, nesting sites.

Mutualism

A relationship between two species in which both species benefit

keytone species

a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.

apex predator

a predator residing at the top of a food chain upon which no other creatures prey

integrity

encourages a full commitment to knowledge and understanding as well as the honest reporting of all sources of information and results

Benefiscence

encourages the maximisation of benefits while minimising the risks and harms involved in taking a particular position or course of action

Non-maleficence

discourages causing harm - or when harm is unavoidable, ensuring that the harm is not disproportionate to the benefits from any position or course of action

Deoxyribonucleic acid (DNA)

a double-stranded nucleic acid chain made up of nucleotides.

Diploid

containing two complete sets of chromosomes, one from each parent.

Chromosomes

threadlike structures made of DNA molecules that contain the genes

Telomeres

DNA at the tips of chromosomes

Centromere

Region of a chromosome where the two sister chromatids attach

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Autosomes

Any chromosome that is not a sex chromosome

sex chromosomes

One of the 23 pairs of chromosomes in the human, contains genes that will determine the sex of the individual.

Polyploidy

condition in which an organism has extra sets of chromosomes

Gametes

reproductive cells

2n chromosomes

diploid

2n-1

monosomy

dominant allele

An allele whose trait always shows up in the organism when the allele is present.

Codominance

situation in which both alleles of a gene contribute to the phenotype of the organism

Codominance example

AB blood type

incomplete dominance example

red flower + white flower = pink flower

X-linked

referring to a gene located on the X chromosome

monohybrid cross

A cross between two individuals, concentrating on only one trait

Punnet Square

a method of predicting the genotypes and phenotypes of offspring in genetic crosses

Population

A group of individuals that belong to the same species and live in the same area

asexual reproduction

A reproductive process that involves only one parent and produces offspring that are identical to the parent.

binary fission

A form of asexual reproduction in which one cell divides to form two identical cells.

Advantages of asexual reproduction

1. no need mate; can live isolate
2. numerous offspring quickly
3. no energy needed for maintenance of reproductive structures
4. good with stable enviroment

Biotic

Describes living factors in the environment.

Immingration

Moving into a population

Predation

An interaction in which one organism kills another for food.

respect

encourages the acknowledgment of the intrinsic value of living things, and considers the welfare, beliefs, customs, and cultural heritage of both the individual and the collective

Justice

encourages fair consideration of competing claims, and ensures that there is no unfair burden on a particular group from an action

Nucleic acid

the class of macromolecules that includes DNA and RNA

Nucleotide

the monomer unit of nucleic acids.

Gene

A segment of DNA on a chromosome that codes for a specific protein

Genome

the complete instructions for making an organism, consisting of all the genetic material in that organism's chromosomes

Allele

An alternative form of a gene.

Locus

Location of a gene on a chromosome

Phenotype

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

Genotype

An organism's genetic makeup, or allele combinations.

Haploid

having a single set of unpaired chromosomes

somatic cells

any cell of a living organism other than the reproductive cells.