Biology II Week 2

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16 16 is half of 32.

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3 These crossover events increase the genetic variation among gametes.

Normal human gametes carry _____ chromosomes.

23 This is the number of chromosomes in a single set of human chromosomes.

Which of these gametes contain one or more recombinant chromosomes?

B, C, F, and G These gametes carry chromosomes produced as a result of crossing over.

Which of these cells are haploid?

C and D Once meiosis I is completed, cells are haploid.

Which of the following statements best describes Darwin's theory of evolution by natural selection?

DARWIN'S THEORY EMPHASIZED THAT POPULATIONS VARY AND CHANGE OVER TIME

Which of the following statements is true of a species that has a chromosome number of 2n = 16?

EACH DIPLOID CELL HAS EIGHT HOMOLOGOUS PAIRS OF CHROMOSOMES

Heritable variation is required for

EVOLUTION

The continuity of life is based on heritable information in the form of DNADNA. Which processes provide perpetuation of parental traits and genetic variation among offspring? Drag the appropriate items to their respective bins.

GENETIC VARIATION: independent assortment of chromosomes; random fertilization; crossing over PERPETUATION OF PARENTAL TRAITS: equal assortment of chromosome sets; transmission of chromosomes from parents to offspring

Describe how sister chromatids and homologous chromosomes differ from each other.

HOMOLOGOUS CHROMOSOMES CONTAIN THE SAME GENE LOCI BUT MAY HAVE DIFFERENT ALLELES OF A PARTICULAR GENE. SISTER CHROMATIDS ARE IDENTICAL COPIES OF EACH OTHER PRODUCED DURING DNA REPLICATION

Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?

MEIOSIS

Human gametes are produced by

MEIOSIS Meiosis produces haploid gametes from a diploid parent cell.

Homologous pairs of chromosomes are lined up independently of other such pairs during

METAPHASE I

In the life cycle of an organism, meiosis is paired with the process of fertilization. Understanding the life cycle of an organism is the key to understanding how sexual reproduction ensures the inheritance of traits from both parents and also introduces genetic variation. Complete the diagram to show the life cycle of a typical animal. Follow these steps: Drag labels of Group 1 to identify each stage of the life cycle. Drag labels of Group 2 to identify the ploidy level at each stage. Drag labels of Group 3 to identify the process by which each stage occurs. Labels can be used once, more than once, or not at all.

Meiosis creates gametes (eggs and sperm) with only a single chromosome set (haploid or n) from parental cells with two chromosome sets (diploid or 2n). During fertilization, the haploid sperm (n) and egg (n) fuse, producing a diploid zygote (2n). The cells of the zygote then divide by mitosis (which does not change the ploidy level) to produce an adult organism (still 2n) of the next generation. In sexual life cycles, meiosis and fertilization keep the number of chromosomes constant from generation to generation.

Crossing over, resulting in an increase in genetic variation, occurs between

NONSISTER CHROMATIDS OF HOMOLOGOUS CHROMOSOMES This process produces chromosomes containing genes inherited from both parents.

In his breeding experiments, Mendel first crossed true-breeding plants to produce a second generation, which were then allowed to self-pollinate to generate the offspring. How do we name these three generations?

P, F1, AND F2

What process facilitates the fastest way for animal species to adapt to a changing environment?

SEXUAL REPRODUCTION

Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Which of the following statements best represents the connection between reproduction and evolution?

SEXUAL REPRODUCTION INCREASES GENETIC VARIATION BECAUSE RANDOM MUTATIONS CAN BE SHUFFLED BETWEEN ORGANISMS

The somatic cells of a particular plant each contain a total of 46 chromosomes. How do the chromosomes of this plant differ from the chromosomes of humans, who also have a total of 46?

THE GENE'S ON THIS PLANT'S LARGEST CHROMOSOME ARE SIGNIFICANTLY DIFFERENT THAN THOSE ON THE LARGEST HUMAN CHROMOSOME

Which of the following sentences state a significant conclusion that Gregor Mendel drew from his experiments with pea plants?

TRAITS ARE INHERITED IN DISCRETE UNITS AND ARE NOT THE RESULT OF "BLENDING"

trans-

across

anti-

against

hem- (or hemato-)

blood

meta-

change, after

trop- (or -tropic)

change, turn, move

hetero-

different, other

dys-

difficult, painful

-ase

enzyme

de-

from, out of, remove

poly-

many

lact-

milk

non-

not

neutr-

of neither gender or type

semi-

one-half

tri-

three

ad-

to

-phil (or philo-)

to love

co-

with or together with

intra-

within