Inheritance, Variation and Evolution

Question 1

What is the function of DNA in cells?

Answer 1

“DNA contains genetic instructions to build proteins, determining inherited characteristics.”

Question 2

Explain how dominant and recessive alleles produce different phenotypes.

Answer 2

“Dominant alleles mask recessive ones; two recessive alleles are needed for the recessive phenotype.”

Question 3

How do gametes differ from normal body cells in chromosome number?

Answer 3

“Gametes have 23 chromosomes (haploid); body cells have 46 (diploid).”

Question 4

What is a mutation?

Answer 4

“A random change in DNA that can create new alleles.”

Question 5

Describe the process of natural selection.

Answer 5

“1. Variation exists. 2. Environmental pressures favor advantageous traits. 3. Survivors pass on alleles. 4. Species evolves.”

Question 6

Why might a species become extinct?

Answer 6

“Rapid environmental change (e.g., climate), new predators, or competition it can’t adapt to.”

Question 7

What is the genome of an organism?

Answer 7

“The entire set of genetic material (DNA) in an organism.”

Question 8

Explain why identical twins have the same DNA.

Answer 8

“They form from a single fertilized egg that splits, so they share identical genetic information.”

Question 9

How does antibiotic resistance develop in bacteria?

Answer 9

“Bacteria with random mutations survive antibiotics, reproduce, and pass on resistance genes.”

Question 10

What is selective breeding?

Answer 10

“Humans breeding organisms over generations to enhance desired traits (e.g., crop yield).”

Question 11

Describe one ethical concern about genetic engineering.

Answer 11

“Risk of unintended effects on ecosystems (e.g., GM crops crossbreeding with wild plants).”

Question 12

What is a chromosome?

Answer 12

“A coiled structure of DNA found in the nucleus, carrying genes.”

Question 13

Explain how fossils provide evidence for evolution.

Answer 13

“Fossils show gradual changes in species over time and links between extinct/modern organisms.”

Question 14

What causes variation in a species?

Answer 14

“Genetic differences (alleles) and environmental factors (e.g., diet).”

Question 15

How does meiosis create genetic variation?

Answer 15

“Crossing over of chromosomes and random mixing of alleles during gamete formation.”

Question 16

What is the difference between genotype and phenotype?

Answer 16

“Genotype = genetic makeup (e.g., Bb); phenotype = observable trait (e.g., brown eyes).”

Question 17

What is evolution?

Answer 17

“The gradual change in species over time through natural selection.”

Question 18

Explain why Darwin’s theory of evolution was controversial.

Answer 18

“It conflicted with religious beliefs and lacked evidence for inheritance mechanisms at the time.”

Question 19

What is a fossil?

Answer 19

“Preserved remains/traces of organisms from millions of years ago.”

Question 20

How does genetic engineering differ from selective breeding?

Answer 20

“Genetic engineering directly alters DNA; selective breeding uses natural reproduction.”

Question 21

What is biodiversity?

Answer 21

“The variety of different species in an ecosystem.”

Question 22

Explain why bacteria can evolve quickly.

Answer 22

“Short life cycles, rapid reproduction, and high mutation rates.”

Question 23

What are the two types of variation?

Answer 23

“Genetic (inherited) and environmental (acquired).”

Question 24

Describe the three-domain system of classification.

Answer 24

“Archaea, Bacteria, Eukaryota (replaced the five-kingdom system).”

Question 25

What is asexual reproduction?

Answer 25

"Reproduction without gametes, producing genetically identical offspring (clones)."

Question 26

Explain how a recessive genetic disorder is inherited.

Answer 26

"Both parents must pass on the recessive allele (e.g., cystic fibrosis)."

Question 27

What is a gamete?

Answer 27

"A sex cell (sperm or egg) with half the chromosomes of a normal cell."

Question 28

How does extinction reduce biodiversity?

Answer 28

"It permanently removes a species, reducing genetic and ecosystem diversity."

Question 29

What is the purpose of the binomial naming system?

Answer 29

"To give species a universal two-part name (Genus species) for clear identification."

Question 30

Explain why Lamarck’s theory of evolution was disproven.

Answer 30

"Acquired traits (e.g., muscle growth) aren’t inherited; genes determine characteristics."

Question 31

What is a hybrid organism?

Answer 31

"The offspring of two different species (e.g., mule), usually infertile."

Question 32

Describe how genetic analysis has improved classification.

Answer 32

"DNA comparisons show evolutionary relationships more accurately than physical traits."

Question 33

What is a vector in genetic engineering?

Answer 33

"A carrier (e.g., plasmid or virus) used to transfer genes into an organism."

Question 34

Explain why Mendel used pea plants for his experiments.

Answer 34

"They reproduce quickly, have clear traits, and he could control pollination."

Question 35

What is an allele?

Answer 35

"A version of a gene (e.g., blue or brown eye allele)."

Question 36

How do fossils form in sedimentary rock?

Answer 36

"Layers of sediment bury remains, minerals replace hard tissues, creating a fossil over time."

Question 37

What is the main advantage of sexual reproduction?

Answer 37

"Increases genetic variation, helping species survive environmental changes."

Question 38

Explain why the fossil record is incomplete.

Answer 38

"Most organisms decompose; fossilization requires rare conditions (e.g., no oxygen)."

Question 39

What is a species?

Answer 39

A group of organisms that can interbreed to produce fertile offspring.