TOPIC 6 - INHERITANCE, VARIATION & EVOLUTION

Full deck of Inheritance, variation and evolution

(What is the difference between meiosis and mitosis?

Meiosis produces non-identical cells while mitosis produces genetically identical cells.)

(What is sexual reproduction?

Reproduction involving the fusion of male and female gametes.)

(What are the gametes in animals?

Sperm and egg cells.)

(What are the gametes in flowering plants?

Pollen and egg cells.)

(Why does sexual reproduction produce variation?

Because genetic information from two parents is mixed.)

(Which type of cell division produces gametes?

Meiosis.)

(What is asexual reproduction?

Reproduction involving one parent and no fusion of gametes.)

(Why does asexual reproduction not produce variation?

There is no mixing of genetic information.)

(What type of offspring does asexual reproduction produce?

Genetically identical offspring called clones.)

(Which type of cell division is involved in asexual reproduction?

Mitosis.)

(Why is meiosis important?

It halves the chromosome number in gametes.)

(Where does meiosis occur?

In reproductive organs.)

(What happens to chromosomes before meiosis?

Genetic information is copied.)

(How many times does the cell divide in meiosis?

Twice.)

(How many gametes are produced in meiosis?

Four.)

(How many sets of chromosomes do gametes contain?

One set.)

(Are gametes genetically identical?

No

(What happens at fertilisation?

Gametes fuse and restore the full number of chromosomes.)

(How does the new cell divide after fertilisation?

By mitosis.)

(What happens to cells as an embryo develops?

Cells differentiate.)

(What is an advantage of sexual reproduction?

It produces variation in offspring.)

(Why is variation beneficial?

It increases survival if the environment changes.)

(How can humans speed up natural selection?

Through selective breeding.)

(What is an advantage of asexual reproduction?

Only one parent is needed.)

(Why is asexual reproduction faster?

No time or energy is spent finding a mate.)

(When is asexual reproduction particularly useful?

When conditions are favourable.)

(Why might organisms reproduce both sexually and asexually?

Different conditions favour different methods.)

(How do malarial parasites reproduce?

Asexually in humans and sexually in mosquitoes.)

(How do many fungi reproduce?

Both sexually and asexually.)

(How do strawberry plants reproduce asexually?

By runners.)

(What is DNA?

A chemical that carries genetic information.)

(Where is DNA found?

In the nucleus of cells.)

(What is the structure of DNA?

Two strands forming a double helix.)

(What structures contain DNA?

Chromosomes.)

(What is a gene?

A small section of DNA on a chromosome.)

(What does a gene code for?

A specific protein.)

(What is the genome?

The entire genetic material of an organism.)

(Why is understanding the human genome important?

It helps identify disease genes

(What is DNA made from?

Repeating units called nucleotides.)

(What are the four bases in DNA?

Adenine

(What does each nucleotide consist of?

A sugar

(What does a sequence of three bases code for?

One amino acid.)

(How does DNA control protein structure?

The order of bases determines the order of amino acids.)

(What forms the backbone of DNA?

Alternating sugar and phosphate groups.)

(Which bases pair together?

A pairs with T and C pairs with G.)

(Where are proteins synthesised?

On ribosomes.)

(Why is protein shape important?

It determines the protein’s function.)

(What is a mutation?

A change in the DNA sequence.)

(Do most mutations affect proteins?

No

(How can mutations affect phenotype?

By changing protein structure or gene expression.)

(What is a gamete?

A sex cell.)

(What is a chromosome?

A structure containing DNA.)

(What is an allele?

A different form of a gene.)

(What is a dominant allele?

An allele that is always expressed if present.)

(What is a recessive allele?

An allele expressed only if two copies are present.)

(What does homozygous mean?

Having two identical alleles.)

(What does heterozygous mean?

Having two different alleles.)

(What is genotype?

The alleles an organism has.)

(What is phenotype?

The characteristics expressed.)

(Are most characteristics controlled by one gene?

No

(What is polydactyly?

A condition of having extra fingers or toes.)

(Is polydactyly caused by a dominant or recessive allele?

A dominant allele.)

(What is cystic fibrosis?

A disorder affecting cell membranes.)

(Is cystic fibrosis caused by a dominant or recessive allele?

A recessive allele.)

(What is embryo screening?

Testing embryos for genetic disorders.)

(Why is embryo screening controversial?

It raises ethical

(How many chromosome pairs do human body cells have?

23 pairs.)

(How many pairs determine sex?

One pair.)

(What are the sex chromosomes in females?

XX.)

(What are the sex chromosomes in males?

XY.)

(Which parent determines the sex of the baby?

The father.)

(What is variation?

Differences in characteristics within a population.)

(What causes genetic variation?

Differences in inherited genes.)

(What causes environmental variation?

Differences in conditions such as diet or climate.)

(Can variation be caused by both genes and environment?

Yes.)

(Where do all genetic variants originate?

Mutations.)

(How often do mutations lead to new phenotypes?

Very rarely.)

(When can a new phenotype spread rapidly?

If it is suited to an environmental change.)

(What is evolution?

A change in inherited characteristics over time.)

(What drives evolution?

Natural selection.)

(What is natural selection?

The process where better-adapted individuals survive and reproduce.)

(When does speciation occur?

When populations can no longer interbreed to produce fertile offspring.)

(What is selective breeding?

Humans breeding organisms for desired traits.)

(How long has selective breeding been used?

For thousands of years.)

(What are examples of selective breeding?

Disease-resistant crops and high-yield animals.)

(What is a risk of selective breeding?

Inbreeding and inherited defects.)

(What is genetic engineering?

Modifying an organism’s genome by adding a gene from another organism.)

(Why are GM crops produced?

For higher yields or resistance to pests and disease.)

(Why are bacteria genetically engineered?

To produce substances like human insulin.)

(What are concerns about GM crops?

Effects on ecosystems and human health.)

(What is the role of enzymes in genetic engineering?

To cut out and insert genes.)

(What is a vector?

A carrier such as a plasmid or virus.)

(What is tissue culture?

Growing identical plants from small groups of cells.)

(What are cuttings?

Producing new plants from parts of a parent plant.)

(What are embryo transplants?

Splitting embryos to produce identical animals.)

(What is adult cell cloning?

Replacing the nucleus of an egg cell with an adult cell nucleus.)

(Why is cloning controversial?

Ethical concerns and low success rates.)

(Who proposed the theory of evolution by natural selection?

Charles Darwin.)

(When was On the Origin of Species published?

1859.)

(Why was Darwin’s theory controversial?

It challenged religious beliefs and lacked early evidence.)