ib 2 nd semester review

IB 2nd Semester Review

Campbell Chapters 13, 14, 15, 20

Directions

• Work in a group of 3-4 students • We will go group by group to answer a question.• If a group cannot answer a question correctly,

the first group to raise their hand and is called on may answer the question.

• There is no penalty for guessing. • Team with the most points at the end wins! • I may deduct points for disruptive behavior …

Here we go …

Good luck!

Define: meiosis

A type of cell division that produces gametes; reduces

chromosome number by half

Multiple Choice

How does the sexual life cycle increase the genetic variation in a species?

• a. by allowing independent assortment of chromosomes

• b. by allowing random fertilization

• c. by allowing crossing over

• d. A and B only• e. A, B, and C

Multiple Choice

• A plant with purple flowers is allowed to self-pollinate. Generation after generation, it produces purple flowers. This is an example of …

• A. Hybridization• B. Incomplete

dominance • C. True-breeding• D. The law of

segregation • E. Polygenetics

Multiple Choice

• Which of the following statements about Mendel's breeding experiments is correct?

• a. None of the parental (P) plants were true-breeding.

• b. All of the F2 progeny showed a phenotype that was intermediate between the two parental (P) phenotypes.

• c. Half of the F1 progeny had the same phenotype as one of the parental (P) plants, and the other half had the same phenotype as the other parent.

• d. All of the F1 progeny resembled one of the parental (P) plants, but only some of the F2 progeny did.

• e. none of the above

Multiple Choice What is the difference between a monohybrid cross

and a dihybrid cross?

• a. A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.• b. A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two

progeny.• c. A monohybrid cross involves organisms that are heterozygous for a single character, whereas

a dihybrid cross involves organisms that are heterozygous for two characters.• d. A monohybrid cross is performed only once, whereas a dihybrid cross is performed twice.• e. A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio.

Multiple Choice

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates

• a. the blending model of genetics.

• b. true-breeding.

• c. dominance.

• d. a dihybrid cross.

• e. the mistakes made by Mendel.

Multiple Choice

The F1 offspring of Mendel's classic pea cross always looked like one of the two parental

varieties because …

• a. one allele was completely dominant over another.• b. each allele affected phenotypic expression.• c. the traits blended together during fertilization.• d. no genes interacted to produce the parental phenotype.• e. different genes interacted to produce the parental phenotype.

Multiple Choice

Which of the following is (are) true for alleles?

• a. They can be identical or different for any given gene in a somatic cell.

• b. They can be dominant or recessive.• c. They can represent alternative forms of a gene.• d. Only A and B are correct.• e. A, B, and C are correct.

Two plants are crossed, resulting in offspring with 3:1 ratio for a

particular trait. This suggests …

That the parents were both heterozygous.

A 9:3:3:1 phenotypic ratio is characteristic of what type of

cross? Dihybrid

Why was it important that Mendel examine not just the F1

generation, but the F2 generation as well?

Parental traits that were not observed in the F1 reappeared in the F2,

suggesting that the traits did not truly disappear in the F1.

When crossing a homozygous recessive with a heterozygote,

what is the chance of getting an offspring with the homozygous

recessive phenotype?

50%

In a particular plant, leaf color is controlled by gene D. Plants with the dominant allele D have dark green leaves, and plants with the homozygous recessive dd genotype

have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of this

cross is diagrammed in the Punnett square shown below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.

Which of the boxes marked 1-4 correspond to plants with dark leaves?

In a particular plant, leaf color is controlled by gene D. Plants with the dominant allele D have dark green leaves, and plants with the homozygous recessive dd genotype

have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of this

cross is diagrammed in the Punnett square shown below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.

Which of the boxes correspond to plants with a heterozygous genotype?

In a particular plant, leaf color is controlled by gene D. Plants with the dominant allele D have dark green leaves, and plants with the homozygous recessive dd genotype

have light green leaves. A true-breeding dark-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of this

cross is diagrammed in the Punnett square shown below, where 1, 2, 3, and 4 represent the genotypes corresponding to each box within the square.

Which of the plants will be true breeding?

What are Punnett squares used for?

Predicting the result of genetic crosses between organisms of

known genotypes

Black fur in mice (B) is dominant to brown fur (b) Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt x BBtt will have black fur

and long tails?

½

What fraction of this cross will be recessive for both traits?

• 1/16

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall

plant, what is the probability that the offspring will be short?

0

What is a genome?

The complete complement/sequence of an

organism’s genes

How are asexual reproduction and sexual reproduction

different? Sexual: genetically different offspring;

meiosis; 2 parentsAsexual: genetically identical offspring;

mitosis; 1 parent

What is a karyotype?

A display of every pair of homologous chromosomes within a cell, organized

according to size and shape

What are the two methods used to obtain cells to create a

karyotype? Amniocentesis & chorionic villus

sampling

Where/how are cells obtained during amniocentesis?

Needle/abdomen amniotic fluid drawn

Where/how are cells drawn during chorionic villus sampling?

Villus cells from the placenta are removed and analyzed; tube inserted

through vagina and cervix into the placenta

What is the term for a human cell that contains 22 pairs of autosomes and two X

chromosomes?

A female somatic cell

The numbers in Figure 10-1 represent the chromosome number found in each of the dog

cells shown. The processes that are occurring at A and B are ____.

• a. mitosis and fertilization• b. mitosis and pollination• c. meiosis and fertilization• d. meiosis and pollination

Fertilization results in …

A zygote

Meiosis results in …

Gametes; 4 genetically different haploid cells

Consider the cell labeled X in Figure 10-9 containing 4 chromosomes. Which of the four cells below it represents a healthy gamete that could be

produced from this cell?

• A

Why is it important gametes are haploid and not diploid?

Haploid + haploid = diploid (zygote) right number of

chromosomes (46)

Fill in the blanks:

Gametes are _____ & somatic cells are _____

Haploid, diploid

What is another term that is synonymous to: synapsis, tetrads, and chiasmata?

Crossing over

Crossing over happens during which phase of meiosis?

Prophase 1

Tetrads line up at the center of the cell in which phase of

meiosis? Metaphase 1

Sister chromatids separate during which phase of meiosis?

Anaphase 2

Which of the following occurs in meiosis but not mitosis: chromosome replication,

synapsis, production of daughter cells, alignment of tetrads at

metaphase plate?

Synapsis & alignment of tetrads

Why is crossing over significant?

Exchange of genetic material – genetic diversity