inheritance variation and evolution

What is inheritance?

Passing of genetic information from parents to offspring

What is a gene?

Segment of DNA coding for a specific trait/protein

What is a chromosome?

Thread-like structure carrying genetic material

How many chromosomes do humans have?

46 (23 pairs)

What is DNA?

Deoxyribonucleic acid, carrier of genetic information

What is genotype?

Genetic makeup of an organism

What is phenotype?

Visible characteristics/traits of an organism

What is an allele?

Different form of a gene

What is homozygous?

Having two identical alleles

What is heterozygous?

Having two different alleles

What is dominant allele?

Allele that is expressed if present

What is recessive allele?

Allele only expressed when two copies present

What is a Punnett square?

Diagram predicting genetic cross outcomes

What is gamete?

Sex cell (sperm or egg)

What is fertilisation?

Fusion of male and female gametes

What is sexual reproduction?

Production of offspring with genetic variation from two parents

What is asexual reproduction?

Offspring produced from single parent; no genetic variation

How does asexual reproduction occur?

Mitosis

How does sexual reproduction occur?

Meiosis

What is meiosis?

Cell division producing gametes with half usual chromosome number

What is mitosis?

Cell division producing identical cells for growth and repair

Why is variation important?

Allows survival and adaptation to changing environment

What is genetic variation?

Differences in DNA among individuals

What is environmental variation?

Differences caused by surroundings (e.g., climate, diet)

Name a trait affected by both genes and environment.

Height, weight, skin color

What is mutation?

Change in DNA sequence

How do mutations occur?

Naturally or by radiation/chemicals; random

What can mutations cause?

New traits, diseases, beneficial/adverse effects

What is evolution?

Gradual change in species over time

Who developed the theory of evolution by natural selection?

Charles Darwin

What is natural selection?

Best-adapted survive, reproduce, pass on genes

What are fossils?

Remains or impressions of ancient life in rocks

How do fossils form?

From hard parts, impressions, or preservation in amber/ice

What evidence do fossils provide?

Life changed over time/evolution

Why is the fossil record incomplete?

Not all organisms fossilize, fossils destroyed, not found

What is extinction?

All members of a species die out

What causes extinction?

Environmental changes, new predators, disease, competition, catastrophic events

What is selective breeding?

Choosing parents with desirable traits for breeding

Why is selective breeding done?

Produce crops/animals with useful features

Give an example of selective breeding.

Disease-resistant crops, high milk yield cows

What are risks of selective breeding?

Reduced variation, more genetic disorders

What is genetic engineering?

Altering DNA to introduce new traits

How is genetic engineering done?

Genes inserted into organisms using enzymes/vectors

Give a use of genetic engineering.

GM crops, insulin production

What is a vector in genetic engineering?

Carrier of desired gene (plasmid or virus)

What are GM crops?

Crops genetically modified for improved features

Name one ethical concern about GM crops.

Possible health/environmental effects

What is cloning?

Making genetically identical copies of organisms

Give 2 types of cloning.

Tissue culture, embryo cloning, adult cell cloning

What is adult cell cloning?

Replacing nucleus of egg with nucleus from adult cell

What is tissue culture?

Growing cells in nutrient medium to produce clones

What is embryo cloning?

Splitting early embryo to produce identical offspring

How are identical twins formed?

Single fertilised egg splits into two embryos

What is gene therapy?

Replacing faulty genes to cure disease

What is human genome project?

International project to map all human genes

What are advantages of knowing human genome?

Identify disease genes, develop treatments

Give a disadvantage of knowing human genome.

Ethical concerns, privacy, discrimination

What is inherited disorder?

Disease caused by faulty genes

Give an example of inherited disorder.

Cystic fibrosis, sickle cell anaemia

How is cystic fibrosis inherited?

Recessive allele from both parents

What is carrier?

Person with one copy of recessive allele (not affected)

What is pedigree diagram?

Chart showing inheritance patterns in families

How is sex determined in humans?

XX = female, XY = male

What is variation within species called?

Genetic diversity

What does survival of the fittest mean?

Best-suited organisms survive and reproduce

How does antibiotic resistance evolve?

Bacteria with resistance survive and multiply

Why is overuse of antibiotics a problem?

Promotes evolution of resistant bacteria

What is speciation?

Formation of new species from existing species

What can cause speciation?

Isolation, mutation, natural selection

How can animals be isolated?

Geographical barriers (mountains, rivers)

What is adaptation?

Feature helping organism survive in environment

Give an example of animal adaptation.

Polar bear’s thick fur, camel’s hump

Give an example of plant adaptation.

Cactus’ thick stem for water storage

What is discontinuous variation?

Variation with distinct categories (blood type)

What is continuous variation?

Variation with a range of values (height)

What is binomial classification?

Scientific naming of species (Genus, species)

What are the 3 domains of life?

Bacteria, Archaea, Eukaryota

Why do organisms need classification?

To identify, study, understand relationships

What is phylogeny?

Study of evolutionary relationships

What is hybrid?

Offspring from different species/crosses

What is genetic counseling?

Advice about risk of inherited disorders

What is gene pool?

Total genes in a population

Why does migration affect gene pool?

Introduces/removes alleles

What is natural mutation rate?

Frequency of mutations in a population

How do environmental factors cause mutations?

Radiation, UV light, chemicals

What is a genetic cross?

Breeding to study inheritance

What is test cross?

Cross to determine genotype of organism

How does selective breeding reduce genetic diversity?

Removes undesired genes, narrows gene pool

How do fossil discoveries change ideas about evolution?

Provide new evidence, fill gaps

What is paleontology?

Study of fossils

How is DNA analysed?

Using gel electrophoresis, sequencing

Why might GM organisms be patented?

Ownership rights for companies

What does ethical mean?

Relating to morals/values

What is inherited characteristic?

Trait determined by genes

How are inherited disorders screened?

Genetic testing, screening embryos

Why do species become extinct?

Cannot adapt to rapid environmental changes

What is endangered species?

Species at high risk of extinction

Why save endangered species?

Maintain biodiversity, ecosystems

What is biodiversity?

Variety of life in the world or an ecosystem

Why is biodiversity important?

Supports stable ecosystems, medicine, food