Biology End-Topic Test - Year 10 Flashcards
What is Nucleus
Membrane-enclosed organelle inside cell that contains chromosomes
- They contain an array of holes/pores
What is Ribosome
Is the site of protein synthesis in the cell
Ribosome reads messenger RNA sequence and translates into genetic code
What is Centriole
Help determine location of nucleus and other organelles
Plays role in cell division, involved in formation of mitotic spindle
- Essential for separation of chromosomes during mitosis
What was Gregor Mendel’s Results, and How Did He Find Them
Mid-1800s, Mendel accurately concluded that genes exist in pairs (One from each parent), and that they can separate and form pairs again in next generation
- Did this by experimenting on peas
What 2 Principles Did Gregor Mendel Find
Principle of Segregation
Principle of Independent Assortment
What is Principle of Segregation
Traits/Characteristics of living things exist in pairs of genes
Genes must become separated/segregated before passed onto offspring
Every organism inherits one set of genes from mother, one set of genes from father
What is Principle of Independent Assortment
Inheritance of one set of gene from one parent, is independent from inheritance of one set of gene from other parent
- Eg. If you inherit blue eyes from mother, doesn’t mean you also inherit blonde hair and small nose from mother
- They are inherited independently from eachother
How to Determine if Offspring is Male or Female
Every individual has an X chromosome, since both the chromosomes from both eggs of mother has single X chromosome (Meiosis)
For the two sperm cells, one have single X chromosome, one have single Y chromosome
To determine if boy or girl, it is a race between X-sperm and Y-sperm, to see which one fertilises the egg cell first
- If X-sperm fertilises first, it is a girl
- If Y-sperm fertilises first, it is a boy
What is Allele
Different genes for the same characteristic
What is Phenotype
The characteristic or trait itself
What is Genotype
Unique combination of alleles for a gene inherited from parents
- Which combination you get is your phenotype
What is Homozygous
Where individuals have two of the same alleles - Homozygous
- Eg. BB, bb
What is Heterozygous
Where individuals have two different alleles for same gene - Heterozygous
- Eg. Bb
What is Hemizygous
Where individual has only one allele - Hemizygous
- Eg. B, b
What is a Punnet Square
2x2 square which shows genotypes
What is a Sex-Linked Trait
Also known as X-Linked
Autosomes are the 22 pairs of chromosomes that aren’t sex chromosomes
X chromosome larger than Y chromosome
- Sex chromosomes carry sexual characteristics
- Also carry information for non-sexual characteristics, such as blood clotting, red-green colour blindness
Traits & genes that determine them, that are carried on X-Chromosme = Sex-Linked
- Male show deficiencies in these genes more than females, because only one X chromosome
How Does Red-Green Colour Blindness Work
X-Linked Recessive trait
- ‘Red-Green Colour Blindness’ allele is found on X Chromosome
- Trait only appears if no ‘normal’ alleles for gene is present
Colour receptors in retina of eye controlled by gene on X Chromosome
- When gene is defective, colour receptors don’t function properly, therefore cannot distinguish red from green
How Does Haemophilia Work
X-Linked Recessive disorder
Disease that prevents blood from clotting
Occurs when X-Linked gene that controls clotting factors is defective
What is Co-Dominance
When both alleles are dominant
Both alleles in genotype are seen in phenotype
What is Heterozygous in Co-Dominance
Individual shows both alleles expressed fully in some way
Capital letter represents one of the codominant alleles
- Different capital letter represents other codominant allele so that two don’t get mixed up
What is Incomplete Dominance
When both alleles are dominant
A mixture of alleles in genotype is seen in phenotype
What is Heterozygous in Incomplete Dominance
Individual shows both alleles expressed in combined way
Normally capital letter preresents one of incompletely dominant alleles
- Different capital letter represents other incompletely dominant allele
What is Species
Population capabile of interacting with eachother and breeding and forming fertile offspring
- Need to be able to make babies of their own
What is Variation
Difference between individuals within a species
Many charactersitcis have contributions from several genes
- Eg. Ability to roll tongue is governed by 1 gene
Some variations aren’t genetic
- Environmental Affects (Eg. Region a plant is grown)
Mutation is source of new variation
How Are Characteristics of Population Determined
Characteristics of population determined by combination of environment and gene pool
- Gene Pool - Total of all genes existing in population, responsible for variation in population
– Mutation & Natural Selection can change gene pool
What is Population
Group of organisms of same species living in same area at same time
People in Perth considered population because we interact with each other
- Cannot interact with people in China, unless we cross barriers = Not same population
What Do Animals Compete For
Animals compete for:
- Foods
- Shelter
- Mates
– Eg. Peacocks have coloured feathers attract more mates, increasing chance of reproducing
What is Natural Selection
Most species produce large number of offspring so “the fittest” survive
When environment changes, natural selection will favour the survival of fittest, gene pool will change
- Eventually, changed population may become distinctly different to original population
What Factors Affect Survival Of Organism
Predators
Disease
Competition with its own kind
Availability of food
Heat
Cold
Wind
What Are Selection Pressures
Selection pressures lead to changes in characteristics of population over time through natural selection
What Are Selection Pressures in ‘Pesticide Resistance in Insects’
When insects exposed to pesticides, some individuals may possess genetic variations that make them resistant to effects of pesticide
Resistant individuals have survival advantage, as they can survive & reproduce while susceptible individuals die
Over time, population is dominated by individuals with pesticide-resistant traits, leading to higher prevalence of pesticide resistance in population
What Are Selection Pressures in ‘Antibiotic Resistance in Bacteria’
Bacteria develops resistance to antibiotics through genetic mutations or acquiring resistant genes
When exposed to antibiotics, susceptible bacteria are killed, resistant bacteria
survive & multiply
Population becomes enriched with antibiotic-resistant bacteria, making treatment challenging, leading to spread of drug-resistant strains
What Are Selection Pressures in ‘Rabbit Resistant to Myxomatosis’
Myxomatosis: Viral disease that affects rabbits
When myxomatosis introduced as control measure for rabbits = Caused significant mortality
- Over time, rabbits with genetic resistance to virus survived & reproduced
- Led to emergence of population with higher proportion of rabbitcs with resistance to myxomatosis
What Are Selection Pressures in ‘Bird Beaks on Galapagos Islands’
Galapagos Islands famous for diverse bird species, mainly finches
Beak shapes fo finches adapted to different food sources available on each island
- Eg. Finches with long, thin beaks better suited for getting nectar from flowers
- Eg. Finches with short, stout beaks more effective at cracking seeds
Selection pressure from food sources influenced characteristics of finch population on each island, resulting in variation of beak shapes
What Are Selection Pressures in ‘Coevolution of Flowers and Pollinators’
Flowers & Pollinators often engage in coevolution
Flowers evolve characteristics that attract pollinators
- Like shape, colour, scene, nectar production
- In return, pollinators (Eg. Bees, Birds) evolve traits to efficient access flower’s resources (Eg. Specialised mouthparts or behaviours)
- Leads to mutualistic relationship (Both flowers & pollinators benefit)
What are the Steps to Identifying Pedigree Charts
1) More males or females affected by trait?
- If males, go to 2
- If females, go to 3
2) Do all daughters of affected males have the trait?
- If yes, Sex-Linked Dominant
- If no, go to 4
3) Do all affected children have an affected parent?
- If yes, Autosomal dominant
- If no, go to 5
4) Has a carrier mother passed it onto half/some of her sons?
- If yes, Sex-Linked Recessive
5) Do affected children have unaffected parents
- If yes, Autosomal Recessive
What is Artificial Selection Used in
Agriculture and Crop Improvement
Development of livestock breeds with desirable characteristics
Companion animals and pets
Disease Resistance and Medical Research
What is Geographical or Reproductive Isolation
Organisms separated from one another, preventing exchange of genetic material
Over time, population goes through genetic divergence, getting unique genetic changes, resulting in formation of distinct species
What is the Order of Events For Geographical or Reproductive Isolation
1) Isolation of population
2) Mutations Occur
3) Natural Selections Occur
4) Speciation Occurs (New Species Formed)
