Unit C22 Patterns And Processes

Question 1

What is selective breeding

Answer 1

Choosing parents with desirable traits (physical, behavioral, mental) and have them produce offspring

Question 2

Who was Gregor Mendel?

Answer 2

An Austrian monk in the mid-19th century who studied garden peas to explain inheritance.

Question 3

What does “true-breeding” mean?

Answer 3

Plants that exhibit the same characteristics generation after generation.

Question 4

Why did Mendel use garden peas? (Overall advantage)

Answer 4

They have clear traits, can self- or cross-pollinate, are easy to grow, and have short generations.

Question 5

How are characteristics expressed in peas?

Answer 5

In one of two distinct forms.

Question 6

What are the 7 characteristics Mendel studied in peas?

Answer 6

1. Seed shape
2. Seed colour
3. Pod shape
4. Pod colour
5. Flower colour
6. Flower position
7. Stem length

Question 7

What are the two forms of seed shape?

Answer 7

Wrinkled or smooth.

Question 8

What are examples of contrasting pea traits?

Answer 8

Seed colour: yellow or green
Pod shape: inflated or constricted
Flower colour: purple or white

Question 9

How can garden peas pollinate?

Answer 9

They can self-pollinate or cross-pollinate.

Question 10

Why is self-pollination useful in experiments?

Answer 10

It allows fertilization without another plant and maintains true-breeding lines.

Question 11

Why were peas easy to work with for Mendel?

Answer 11

They are small, easy to grow, and have a short generation time.

Question 12

What did Mendel hypothesize about the seven pea characteristics

Answer 12

That there are alternative forms of genes, the units that determine heredity

Question 13

What happened in Mendel’s P (parent) generation experiment?

Answer 13

Mendel crossed two true-breeding plants: one with purple flowers and one with white flowers.

Question 14

What was the result of the F1 generation?

Answer 14

All offspring had purple flowers, showing purple is the dominant trait.

Question 15

What happened in the F2 generation after F1 plants self-fertilized?

Answer 15

About 75% purple flowers and 25% white flowers (a 3:1 ratio).

Question 16

What is the mixing of 1 trait called

Answer 16

Monohybrid cross

Question 17

What was Mendel studying in the P (parent) generation?

Answer 17

He crossed two true-breeding plants with different traits (ex: purple flowers × white flowers).

Question 18

What does dominant vs recessive mean?

Answer 18

If a dominant gene is present, it overrules the recessive gene and is the trait you see.

Question 19

What is complete dominance?

Answer 19

Only the dominant trait is expressed — no blending or mixing of traits.

Question 20

What is Mendel’s Law of Segregation?

Answer 20

Traits are controlled by pairs of genes, and the gene pairs separate during sex cell formation.

Question 21

What does each parent contribute during reproduction?

Answer 21

One allele for each trait.

Question 22

What are alleles?

Answer 22

Different versions of the same gene.

Question 23

What does homozygous mean?

Answer 23

Two identical alleles (RR or rr).

Question 24

What does heterozygous mean?

Answer 24

Two different alleles (Rr).

Question 25

What is dominance?

Answer 25

One allele can mask another.

Question 26

How are dominant and recessive alleles written?

Answer 26

-Dominant = uppercase letter (R) -Recessive = lowercase letter (r)

Question 27

What happens to gene pairs during meiosis?

Answer 27

They separate, forming haploid sex cells from a diploid parent cell.

Question 28

What is a genotype

Answer 28

Genes Ex, PP Pp pp

Question 29

What is a phenotype

Answer 29

Physical expression (what you see) -ex, purple, white

Question 30

What is in a pair of homologous chromosomes

Answer 30

One inherited from the male patent and the other from the female patent

Question 31

What is a genetic locus

Answer 31

The location of a particular gene on a chromosome

Question 32

What is at each genetic locus?

Answer 32

Two alleles, one on each homologous chromosomes

Question 33

Example of a homozygous dominant

Answer 33

AA

Question 34

Example of a homozygous recessive

Answer 34

bb

Question 35

Example of a heterozygous

Answer 35

Cc

Question 36

What is a monohybrid

Answer 36

Looking at one trait

Question 37

What does a monohybrid cross Ww × Ww represent?

Answer 37

A cross between two heterozygous parents, each carrying two alleles (W and w) for one trait.

Question 38

Why do gametes (eggs and sperm) only carry one allele?

Answer 38

Gametes are haploid, so each carries one allele per trait, even though parents have two.

Question 39

What does the Punnett square show for Ww × Ww?

Answer 39

A 4-box Punnett square showing 4 possible offspring combinations: WW, Ww, Ww, and ww.

Question 40

What is an autosomal recessive monohybrid cross?

Answer 40

A cross involving a trait not affected by sex, where an individual must inherit two recessive alleles to express the trait.

Question 41

What is a test cross?

Answer 41

genetic cross where an individual with a dominant phenotype but unknown genotype is crossed with a homozygous recessive individual to determine the genotype.

Question 42

Why is a homozygous recessive parent used in a test cross?

Answer 42

Because it carries only recessive alleles, so the offspring’s traits reveal the genotype of the unknown parent.

Question 43

What does it mean if all offspring show the dominant trait in a test cross?

Answer 43

The unknown parent is homozygous dominant (true-breeding).

Question 44

What does it mean if offspring show a mix of dominant and recessive traits?

Answer 44

The unknown parent is heterozygous (hybrid).

Question 45

What does the Law of Independent Assortment state?

Answer 45

Genes for different traits assort independently during gamete formation and do not influence each other.

Question 46

During which stage does independent assortment occur, and why?

Answer 46

During Metaphase I of meiosis, because homologous chromosome pairs line up randomly, creating different combinations.

Question 47

What is the result of independent assortment in gametes?

Answer 47

It produces multiple possible allele combinations, increasing genetic variation in offspring.