Biology LS 3-1

BIG IDEA QUESTION: Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristics trait passed from parents to offspring.

1) Chromosomes carry our DNA 2) On our DNA there are genes that code for our instruction to make protein 3) During Meiosis, parents making gametes, the alleles for each gene segregate from one another 4) Therfore, each gamete/sex cell only carries only one allele for each gene Question: How are different forms of a gene passed from parent to offspring? Answer: In sexual reproduction, each parent contributes half of the genes. When gametes are made, the alleles for each trait separate from each other. That way it results in each gamete carrying one allele for each gene. Question: How can genetic information be altered to pass on variations? Answer: Genetic information can be altered because of mutations which can result in beneficial, negative, or no change to proteins or traits of an organism.

A pea plant with yellow seeds was crossed with a plant with green seeds. The F1 generation produced plants with yellow seeds. Explain why green seeds reappeared in the F2 generation.

1) Yellow seeds must be dominant 2) When heterozygous F1 plants produced gametes, their dominant allele for yellow seeds must have segregated from their recessive allele for green seeds 3) As a result, some gametes will have the dominant allele and some gametes will have recessive allele 4) Some male gametes with the recessive allele fertililized with the female gamete that had the recessive allele

Gregor Mendel removed the male parts from the flowers of some plants in order to... a) control crosses between plants b) prevent hybrids from forming c) prevent cross pollination d) stimulate self pollination

A

If a pea plant has recessive allele for green peas, it will produce... a) green peas if it does not also have a dominant allele for yellow peas b) yellow pea if it does not also have a dominant allele for green peas c) green peas if it also has a dominant allele for yellow peas d) both green peas and yellow peas if it also has a dominant allele for yellow peas

A

In the Parental generation, a tall plant was crossed with a short plant. Short plants reappeared in the F2 generation because... a) the alleles for both heights segregated when the F1 plants made gametes b) the allele for shortness becomes more common in the F2 generation c) the alleles for tallness begin to disappear in the F2 generation generation d) the allele for shortness becomes dominant in the F2 generation generation

A

Each pea plant gamete has how many alleles for the height gene? a) 2 b) 1 c) 3 d) 4

B

A tall plant (TT) is crossed with a short plant (tt). if the tall F1 pea plants are allowed to self pollinate... a) the offspring will be medium height b) all of the offspring will be tall c) the offspring can be tall or short d) all of the offspring will be short

C

If a pea plant's alleles for height are tt, what is true of its parents? a) Both parents contributed a dominant allele b) Both parents were short c) Both parents contributed a recessive allele d) Both parents were tall

C

When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inherited... a) four alleles from each parent b) two alleles from each parent c) one allele from each parent d) three alleles from each parent

C

When Gregor Mendel crossed true-breeding tall plants with true-breeding short plants, why was it impossible to observe segregation? a) Alleles segregate best when two tall plants are crossed b) Alleles segregate only in the F2 generation c) Alleles for height do not segregate in the F2 d) Alleles in the F1 must be Tt to have height variety in the F2

D

Due to the process of segregation, alleles separate during the production of ______.

Gametes

The plants that Gregor Mendel crossed to produce the F1 generation made up the ____ generation.

Parental

You wish to determine whether a tall pea plant is homozygous or heterozygous for tallness. What cross should you perform to arrive at your answer? Explain your choice of cross.

Tall plants should be crossed with a short plant. If the tall pea plant is homozygous then all of the offspring will be tall. If the tall pea plant is heterozygous then half the offspring will be tall and the other half is short.