Biology exam revision

Asexual reproduction

No need for 2 parents, one organism that is capable to do reproduction. No need to find a mate. advantage is quick, straight forward process, and we know we are getting an identical match to the parent. The disadvantages are with no genetic variation extinction eg. only 2 different species of bananas so vulnerable, and limited ability to adapt to changing environments because they can’t pass on what we learn.

Asexual reproduction - Binary fission

Is a form of asexual reproduction that involves the splitting of a single organism into 2 daughter cells. eg. bacteria.

Asexual reproduction - Budding

Is a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent organism, often seen in yeasts and some plants.

Asexual reproduction - Cloning

Is a form of asexual reproduction that produces genetically identical organisms from a single parent organism, commonly seen in plants and certain animals.

Asexual reproduction - parthenogenesis

Is a form of asexual reproduction in which an offspring develops from an unfertilised egg, commonly observed in some reptiles, insects, and plants.

Cloning

Ethical concerns around this is if you do it to get a loved one back from death because the genetic identity of the clone may not replicate the original individual's memories or personality because their experience and environment is different.

Good things about things is how it can aid in preserving endangered species or producing genetically uniform crops. For example cloning an success type of weed could result in a decrease of world hunger.

Sexual reproduction

Is a biological process that involves the combination of genetic material from two parent organisms, resulting in offspring with genetic variation. The types are plant(flower, fruit, and seed) and animals(sperm and eggs). Benefits of this are genetic diversity, adaptation to different habitats, and increased resilience to diseases. The limitations of this are the need for two parents, longer time to produce offspring, and potential for harmful genetic combinations.

Meiosis

Occurs in the sex organs (tenses or overs in animals, ovules and anthers in plants) and is a type of cell division that reduces the chromosome number by half, creating gametes for sexual reproduction. PMAT happens twice but the second time has no duplication.

Meiosis stage- Prophase

The first stage of meiosis where homologous chromosomes pair up and exchange genetic material through crossing-over, increasing genetic diversity.

Meiosis stage - Metaphase

The second stage of meiosis where homologous chromosomes align at the metaphase plate, preparing for segregation into daughter cells, they connect to the spindles.

Meiosis stage - Anaphase

The third stage of meiosis where homologous chromosomes are pulled apart to opposite poles of the cell by the spindle fibers, ensuring each daughter cell receives one chromosome from each pair.

Meiosis stage - Telophase 

The final stage of meiosis where the separated homologous chromosomes reach the opposite poles, the nuclear membrane reforms around each set, and the cell undergoes cytokinesis to produce two haploid cells.

Diploid

A cell that contains two complete sets of chromosomes, one from each parent, typically represented as 2n. for example human somatic cells.

Haploid

A cell that contains a single set of chromosomes, typically represented as n, which is half the diploid number. for example sex cells.

Symbiotic relationship - Mutualism

A type of symbiosis where both species benefit from the interaction, such as bees pollinating flowers while obtaining nectar.

Symbiotic relationship - Commensalism

A type of symbiosis where one species benefits while the other is neither helped nor harmed, such as barnacles attaching to a whale.

Symbiotic relationship - Parasitism

A type of symbiosis where one species benefits at the expense of the other, such as a tick feeding on a mammal.

Adaptations

Changes in an organism that enhance its survival and reproduction in a specific environment.

Adaptation - Structural

Physical features of an organism that aid in survival, such as a bird's beak shape.

Adaptation - Behavioural

Changes in an organism's actions or behaviors that enhance its survival and reproduction, such as migratory patterns or feeding strategies.

Adaptation - Physiological

Internal body processes or functions of an organism that enable it to survive and reproduce in its environment, such as temperature regulation or water conservation.

INDIGENOUS PERSPECTIVES ON THE LAND

Seasons

Knowing weather patterns, abundance of plants & animals

Caring for Country

• Humans are part of the ecosystem

• E.g., harvesting of turtles and dugong (large numbers have been hunted for thousands of years without decline)

• Predatory-prey relationship

Mutual Benefit in Interdependence

• Hunting of kangaroos coupled with managed burning of the bush results in higher populations of kangaroos than in similar areas where hunting occurs with no burning

• The new growth after a burn provides more grass and suppresses plants that kangaroos don’t eat

• Mutually beneficial relationship

Ecosystems and bushfire prevention

Large parts of Australia experience extremely high temperatures in the dry season. Combined with a dry and flammable landscape, this leads to often large and dangerous bush fires. For many decades, conservation of bushland based on Western ideals has focussed on preventing fires. Only recently has it been acknowledged that this practice has contributed to some of the largest wildfires in decades, because it allowed the build up of dry undergrowth and debris that would ordinarily be removed by fire every few decades.

In Australia, Aboriginal knowledge of fire use for bush management is beginning to be employed, including the use of back burning and controlled burns. Traditional Aboriginal knowledge of cool fires, soils, and flowering and fruiting of trees can all be used to decide when and where controlled burns can be used to manage the bush, reduce wildfires, and encourage plant growth and animal diversity.

Keystone species

A species that has a much larger impact in an ecosystem than expected based on its size or numbers. If you remove it, or reduce its numbers, the entire ecosystem could collapse. E.g., Bees as pollinators.

Food web

A complex network of interrelated food chains within an ecosystem, illustrating how energy and nutrients circulate among different organisms, including producers, consumers, and decomposers. The impact of removing species from this network can significantly alter the ecosystem dynamics.

Food web - Producer

An organism that produces its own energy from sunlight or inorganic substances, forming the base of the food web. Examples include plants and algae.

Food web - consumer

An organism that obtains energy by feeding on other organisms, playing a critical role in energy transfer within the food web. Examples include herbivores, carnivores, and omnivores.

Food web - decomposer

An organism that breaks down dead or decaying organic matter, recycling nutrients back into the ecosystem. Examples include fungi, bacteria, and detritivores.

Distribution

The way in which individuals or populations are spread across a specific area or habitat. It can be influenced by various factors including environmental conditions, resources, and interactions with other species.

Abundance

The total number of individuals of a species present in a given area or ecosystem. It reflects the population size and can influence community dynamics.

Density

The number of individuals of a species per unit area or volume, indicating how crowded or sparse a population is within a specific habitat.

Karyotype

A visual representation of the complete set of chromosomes in an organism, organised by size and shape, typically used to identify chromosomal abnormalities. eg. all of the human chromosomes.

Genotype

The genetic constitution of an individual, representing the specific alleles inherited from both parents. It influences the physical traits and characteristics of the organism.

Phenotype

The physical appearance or characteristic traits of an organism resulting from the interaction of its genotype with the environment.

Chromosomes

Structures within cells that contain DNA and play a key role in heredity and cell division.

Alleles

Different forms of a gene that arise by mutation and are found at the same place on a chromosome. They determine specific traits and can be dominant or recessive.

Homologous

chromosomes that share the same structure and gene sequence, one inherited from each parent.

Chromatids

Identical copies of a chromosome that are formed during DNA replication, connected by a centromere.

Mendelian genetics (complete dominance)

A type of inheritance where one allele is completely dominant over another, resulting in offspring that display the dominant trait in the phenotype.

Co-dominance

A type of inheritance where both alleles in a gene pair are fully expressed in the phenotype of the offspring, resulting in a blended or patched appearance of traits. eg. if one dog is black and has an off spring with a white dog they offspring will be black and white spotted.

Incomplete dominance

A type of inheritance where the phenotype of the heterozygote is intermediate between the phenotypes of the homozygotes, resulting in a blending of traits. For example, a red flower crossed with a white flower may produce pink flowers.

Continuous variation

A range of phenotypes that display gradual differences rather than discrete categories, resulting from the interaction of multiple genes and environmental factors. Examples include height and skin color in humans.

How to write ratios and percentage for a punnet square

written by comparing the different genotypic or phenotypic outcomes from a Punnett square. For example, if a cross yields a ratio of 3:1 for dominant to recessive traits, it can also be expressed as 75% dominant and 25% recessive.

Autosomal dominant

A pattern of inheritance where only one copy of a dominant allele is needed for the phenotype to be expressed. Conditions caused by autosomal dominant alleles include Huntington's disease and Marfan syndrome.

Autosomal recessive

A pattern of inheritance where two copies of a recessive allele are necessary for the phenotype to be expressed. Conditions such as cystic fibrosis and sickle cell anemia follow this inheritance pattern.

Sex linked dominant

A pattern of inheritance where a dominant allele located on a sex chromosome affects the phenotype in both males and females. Conditions such as X-linked hypophosphatemia follow this inheritance pattern.

Sex linked recessive

A pattern of inheritance where a recessive allele located on a sex chromosome is expressed predominantly in males, as they have only one X chromosome. Conditions such as hemophilia and Duchenne muscular dystrophy are examples of this inheritance pattern.

Fossils - Relative dating

The method of determining the age of fossils by comparing their placement within sedimentary rock layers, allowing scientists to estimate the time period in which the organism existed.

Fossils - Absolute dating

A method for determining the age of fossils based on the decay of radioactive isotopes, providing a specific age estimate. C-14 decay is commonly used for dating organic material up to about 50,000 years old. Radioactivity is used to measure the age of rocks and fossils, giving a precise numerical age.

Trends (Skeletal and brains)

Changes in skeletal structure and brain size over evolutionary time, reflecting adaptations to environmental demands and species development. Problems include variations among species and the influence of convergent evolution. Advantages are bipedalism and having larger brains.