Biology Chapter: Genetics and Reproduction

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Questions and Answers

What is the general term for the transmission of traits from one generation to the next?

Inheritance (correct)

Heredity (correct)

Variation

Genetics

Which of the following is NOT true about genes?

Genes are located on chromosomes.

Genes are segments of DNA.

Genes are passed to the next generation through gametes.

Genes are responsible for influencing all physical traits, but not behavioral traits. (correct)

What type of cell division is involved in the production of gametes?

Meiosis (correct)

Budding

Binary fission

Mitosis

What is the specific location of a gene on a chromosome called?

Locus (B) Signup and view all the answers

Which of these is a characteristic of asexual reproduction?

Produces genetically identical offspring. (A) Signup and view all the answers

What is the term used to describe an individual or group of genetically identical individuals from the same parent?

Clone (C) Signup and view all the answers

What is the significance of understanding life cycles?

All of the above. (D) Signup and view all the answers

Which is NOT a key characteristic of a life cycle?

Is unique for all organisms. (B) Signup and view all the answers

What is the total number of chromosomes found in human somatic cells?

46 (D) Signup and view all the answers

What type of chromosomes do human females have in their sex chromosomes?

XX (B) Signup and view all the answers

Which of the following statements about homologous chromosomes is true?

They contain genes controlling the same inherited characters. (A) Signup and view all the answers

What is the haploid number of chromosomes in human gametes?

23 (A) Signup and view all the answers

In what type of cell division are gametes produced?

Meiosis (B) Signup and view all the answers

What is the fertilized egg called?

Zygote (D) Signup and view all the answers

How many pairs of chromosomes do human somatic cells have?

23 (B) Signup and view all the answers

Which chromosomes are referred to as autosomes?

The first 22 pairs of chromosomes (C) Signup and view all the answers

What occurs during metaphase II of meiosis?

Sister chromatids are aligned at the metaphase plate. (B) Signup and view all the answers

What is the result of crossing over during prophase I?

Nonsister chromatids exchange genetic material. (C) Signup and view all the answers

What is formed at the end of meiosis?

Four genetically distinct daughter cells. (B) Signup and view all the answers

During which phase do sister chromatids separate?

Anaphase II (B) Signup and view all the answers

What structures attach to the kinetochores during metaphase II?

Microtubules (A) Signup and view all the answers

What is the primary difference between mitosis and meiosis?

Meiosis involves crossing over; mitosis does not. (A) Signup and view all the answers

What happens to chromosomes at the end of telophase II?

They arrive at opposite poles and nuclei form. (D) Signup and view all the answers

What is the main role of the synaptonemal complex during prophase I?

To hold homologous chromosomes together tightly. (C) Signup and view all the answers

What is the role of cohesins during meiosis in relation to sister chromatids?

They prevent sister chromatids from separating. (B) Signup and view all the answers

What is considered the original source of genetic diversity?

Mutations (C) Signup and view all the answers

How does independent assortment affect genetic variation?

It allows maternal and paternal chromosomes to assort into daughter cells randomly. (B) Signup and view all the answers

What is the significance of crossing over in genetic variation?

It combines maternal and paternal DNA into one chromosome. (A) Signup and view all the answers

What formula describes the number of combinations of chromosomes due to independent assortment?

$2^n$ where $n$ is the haploid number. (B) Signup and view all the answers

What is the average number of crossover events per chromosome in humans?

One to three (D) Signup and view all the answers

Which of the following mechanisms does NOT contribute to genetic variation?

Cell division without genetic recombination (D) Signup and view all the answers

What defines sister chromatid cohesion?

Sister chromatids are closely associated along their lengths. (A) Signup and view all the answers

Which phase of meiosis is associated with the random orientation of homologous chromosomes?

Metaphase I (A) Signup and view all the answers

During which phase of meiosis I does crossing over occur?

Prophase I (B) Signup and view all the answers

What role do microtubules play during metaphase I?

They attach to the kinetochore of chromosomes. (C) Signup and view all the answers

What does not occur between meiosis I and meiosis II?

Chromosome replication (B) Signup and view all the answers

What is the primary similarity between meiosis II and mitosis?

Both processes separate sister chromatids. (C) Signup and view all the answers

During which phase of meiosis II do chromosomes align at the metaphase plate?

Metaphase II (D) Signup and view all the answers

What is the role of gametes in most animals?

They are produced by meiosis. (D) Signup and view all the answers

In plants and some algae, what is the multicellular diploid organism called?

Sporophyte (B) Signup and view all the answers

In the sexual life cycle of most fungi, what is unique about the diploid stage?

It is represented only by the zygote. (D) Signup and view all the answers

Which statement accurately describes the process of meiosis?

It reduces the chromosome number from diploid to haploid. (D) Signup and view all the answers

What type of organism grows from a haploid spore in the alternation of generations?

Gametophyte (C) Signup and view all the answers

Which of the following is true regarding the cells that undergo meiosis?

Diploid cells are the only ones that can undergo meiosis. (D) Signup and view all the answers

What is the outcome of meiosis in terms of chromosome quantity?

Four daughter cells with half the number of chromosomes as the parent. (A) Signup and view all the answers

What contributes to genetic variation in offspring during sexual reproduction?

The halving of chromosomes (B) Signup and view all the answers

What term refers to a heritable feature that varies among individuals?

Character (D) Signup and view all the answers

Which of the following best describes the 'blending hypothesis' of heredity that was prevalent before Mendel's work?

Offspring inherit a mix of traits, resulting in an intermediate expression. (C) Signup and view all the answers

When true-breeding pea plants with purple flowers are crossed with true-breeding pea plants with white flowers, what color flowers do the F1 generation have?

Purple (A) Signup and view all the answers

What is the key advantage of using pea plants for genetic studies, as demonstrated by Mendel?

All of the above. (D) Signup and view all the answers

What term describes the offspring produced from a cross between two true-breeding varieties?

F1 generation (C) Signup and view all the answers

Which of the following is NOT a key advantage of using peas in Mendel's experiments?

They are difficult to cross-pollinate. (B) Signup and view all the answers

In Mendel's experiments, what was the phenotypic ratio of the F2 generation in a monohybrid cross involving a single character, such as flower color?

3:1 (D) Signup and view all the answers

What key principle did Mendel deduce from his experiments, which states that allele pairs separate during gamete formation and randomly reunite during fertilization?

Law of Segregation (D) Signup and view all the answers

What makes the sickle cell trait unusually common in African-Americans?

It provides resistance to malaria, a common disease in regions where African-Americans originate. (A) Signup and view all the answers

What is the primary cause of the high frequency of sickle cell trait in African-Americans?

Natural selection favoring heterozygotes in malaria-prone regions. (C) Signup and view all the answers

Which of the following is a characteristic of Huntington’s disease?

It is a dominant disorder with delayed onset, meaning symptoms typically appear later in life. (D) Signup and view all the answers

Which of the following diseases is NOT considered a multifactorial disorder?

Sickle-cell anemia (B) Signup and view all the answers

What is the primary role of genetic counseling in cases involving recessive inherited diseases?

To provide information and assess the risk of a couple having a child with the disease. (B) Signup and view all the answers

What is the significance of the statement that 'each child represents an independent event' in relation to inherited disease risk?

The genotype of each child is not influenced by the genotypes of previous siblings. (A) Signup and view all the answers

How does a genetic counselor assist a couple who are both at risk of carrying a recessive allele for a disease?

They can use probability rules and Mendelian genetics to assess the chance of having a child affected by the disease. (C) Signup and view all the answers

Which of these is TRUE regarding multifactorial disorders?

They are characterized by a complex interplay of genetic and environmental factors. (D) Signup and view all the answers

What was the observed phenotypic ratio of purple to white flowers in the F2 generation?

3:1 (A) Signup and view all the answers

What did Mendel name the flower color trait that expressed itself in the F1 hybrids?

Dominant trait (A) Signup and view all the answers

Which term refers to the alternative versions of a gene for a given trait?

Alleles (B) Signup and view all the answers

In the case of flower color, what determines the organism's appearance when the two alleles at a locus differ?

Dominant allele (C) Signup and view all the answers

What concept did Mendel develop to explain the inheritance pattern he observed?

Model of inheritance (B) Signup and view all the answers

What happens to the recessive trait in the F2 generation when crossed from F1 hybrids?

It reappears in certain plants (D) Signup and view all the answers

Which statement accurately reflects Mendel's findings about allele inheritance?

Two alleles inherited can be different from each parent (A) Signup and view all the answers

What is the current term for what Mendel called a 'heritable factor'?

Gene (A) Signup and view all the answers

What characteristic defines individual carriers of recessively inherited disorders?

They are phenotypically normal but carry one recessive allele. (D) Signup and view all the answers

How does consanguineous mating affect the likelihood of recessively inherited disorders?

It increases the likelihood of both parents carrying the same rare allele. (B) Signup and view all the answers

What is a common symptom associated with cystic fibrosis?

Mucus buildup in internal organs (A) Signup and view all the answers

Which statement is true regarding the inheritance of cystic fibrosis?

Symptoms typically appear in individuals who are homozygous for the cystic fibrosis allele. (C) Signup and view all the answers

What is the prevalence of sickle-cell disease among African-Americans?

1 out of 400 (C) Signup and view all the answers

What is a major consequence of untreated cystic fibrosis?

Possible death by age five (C) Signup and view all the answers

What factor increases the chance of recessive disorders appearing in offspring?

Higher rates of consanguinity among parents (C) Signup and view all the answers

What is a notable physical condition caused by sickle-cell disease?

Organ damage due to misshaped red blood cells (B) Signup and view all the answers

What does Mendel's law of independent assortment state?

Each pair of alleles segregates independently of any other pair during gamete formation. (D) Signup and view all the answers

In a dihybrid cross, what is the purpose of crossing two true-breeding parents differing in two characters?

To create dihybrids that are heterozygous for both traits. (A) Signup and view all the answers

How can the probability of obtaining a heterozygous F2 plant from a monohybrid cross be determined?

By using the addition rule for heterozygous events. (A) Signup and view all the answers

What does the multiplication rule in genetics refer to?

Finding the product of the probabilities of two independent events occurring together. (D) Signup and view all the answers

Under what condition does the law of independent assortment apply?

To genes that are located on nonhomologous chromosomes. (D) Signup and view all the answers

Which of the following is true regarding the segregation of alleles?

Each gene's alleles segregate independently during gamete formation. (D) Signup and view all the answers

What is the result of a dihybrid cross between two F1 dihybrids?

It tests the linkage of two traits to confirm independent assortment. (A) Signup and view all the answers

What does the addition rule calculate in a genetic context?

The probability of mutually exclusive outcomes occurring. (D) Signup and view all the answers

What is the expected phenotypic ratio for a dihybrid cross involving epistatic interactions?

9:3:4:0 (B) Signup and view all the answers

Which of the following is an example of polygenic inheritance?

Height in humans (A) Signup and view all the answers

What is the term used to describe traits that are influenced by both genetic factors and environmental influences?

Multifactorial (A) Signup and view all the answers

Which of these is NOT a reason why humans are considered poor subjects for genetic research?

Difficult to track family history (C) Signup and view all the answers

What is the primary tool used in human genetics to analyze the inheritance of traits across generations?

Pedigree (D) Signup and view all the answers

What is the broadest phenotypic range observed in?

Traits controlled by two or more genes (D) Signup and view all the answers

Which of the following statements is TRUE regarding human genetics?

Human genetics research utilizes pedigree analysis to study the transmission of traits. (C) Signup and view all the answers

Which of these is NOT a characteristic of polygenic inheritance?

Typically involves a clear-cut distinction between phenotypes. (A) Signup and view all the answers

Study Notes

Meiosis and Sexual Life Cycles

Meiosis is a specialized cell division that produces gametes (sperm and eggs).
Human cells have 46 chromosomes; only one pair of homologous chromosomes are illustrated in the diagrams.
Chromosomes are duplicated in preparation for meiosis.
Meiosis I separates homologous chromosomes.
Meiosis II separates sister chromatids, resulting in four haploid cells.
Fertilization combines the sperm (n) and egg (n), creating a zygote (2n).
Meiosis occurs only in specialized cells.

Inheritance of Genes

Genes are units of heredity composed of DNA segments.
Genes are passed to the next generation via gametes.
Most DNA is organized into chromosomes.
Humans have 46 chromosomes in somatic cells (except gametes and their precursors).
A gene's location on a chromosome is called its locus.

Comparison of Asexual and Sexual Reproduction

In asexual reproduction, a single parent passes all its genes to offspring without gamete fusion.
A clone is a genetically identical copy of a parent or group of parents.
In sexual reproduction, two parents contribute genetic material to offspring, resulting in unique combinations of genes.

Behavior of Chromosome Sets in the Human Life Cycle

Fertilization is the union of sperm and egg, creating a zygote.
The zygote develops into an adult through mitosis.
In humans, diploid cells have 23 chromosome pairs; gametes have only one set (23).
Gametes are produced through meiosis; while somatic cells are produced by mitosis.

Sets of Chromosomes in Human Cells

Humans have 23 pairs of chromosomes in somatic cells.
A karyotype is a visualization of chromosome pairs.
Homologous chromosomes are chromosome pairs with the same length, centromere position, and staining pattern, carrying genes for the same traits.
The sex chromosomes, which determine sex of the individual, are called X and Y
Human females have a homologous pair of X chromosomes (XX)
Human males have one X and one Y chromosome
The remaining 22 pairs of chromosomes are called autosomes.

Meiosis Reduces Chromosome Sets

Meiosis is a process that results in four haploid daughter cells, each with only one set of chromosomes.
Meiosis involves two rounds of division (Meiosis I and II).
Meiosis I separates homologous chromosomes and Meiosis II separates sister chromatids.
Meiosis contributes to genetic variation through independent assortment of chromosomes and crossing over.

Crossing Over and Synapsis During Prophase I

Crossing over occurs during Prophase I of meiosis.
Nonsister chromatids exchange segments of DNA during this process, creating new combinations of genetic material.
Chiasmata (X shaped regions) are where DNA segments swap during crossing over.

A Comparison of Mitosis and Meiosis

Mitosis produces two genetically identical daughter cells, preserving the same number of chromosomes, while meiosis produces 4 genetically unique daughter cells with one set of chromosomes.

Independent Assortment of Chromosomes

During metaphase I, homologous chromosomes align randomly at the metaphase plate, ensuring random distribution of maternal and paternal chromosomes into daughter cells.
The number of combinations possible from independent assortment is 2ⁿ, where n is the haploid chromosome number.

Crossing Over

Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes (prophase I), leading to recombinant chromosomes.
Crossing over contributes to genetic variation by combining DNA from each parent.

Random Fertilization

Random fertilization results from the joining of any sperm with any egg, further increasing genetic variation in offspring.

The Evolutionary Significance of Genetic Variation Within Populations

Natural selection favors genetic variations that benefit survival and reproduction.
Mutations are the source of new genetic material, and sexual reproduction facilitates the blending and mixing of genes, driving evolution.

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Description

Test your knowledge on key concepts of genetics, including the transmission of traits, types of cell division, and the characteristics of life cycles. This quiz covers important topics such as genes, chromosomes, and reproduction methods. Perfect for biology students looking to reinforce their understanding of inheritance and cellular processes.