Biology chapter 8 test

skib

During which phase does the mitotic spindle pull chromatids toward the centrosomes?

Anaphase

What is the key difference between mitosis and meiosis in terms of genetic variation?

Mitosis produces genetically identical cells; meiosis produces genetically different cells due to crossing over and independent assortment

Do all organisms have the same number of chromosomes?

False (different species have different chromosome numbers)

What type of stem cells are used in bone marrow transplants?

Somatic (adult) stem cells

How does a sex chromosome differ from an autosome?

Sex chromosomes determine male or female sex and carry sex-related genes; autosomes carry genes for body traits and are the same size in a pair

During which phase do centromeres split and chromatids separate?

Meiosis II (specifically Anaphase II)

What are three factors that can affect gene expression besides promoters and regulatory proteins?

Environmental factors like light, temperature, and chemicals/drugs/hormones

What range of cell types can totipotent cells differentiate into?

Any kind of cell

What term describes chromosome pairs that contain the same genes?

Homologous chromosomes

During which phase does the cell grow normally?

Interphase

Why is red-green colorblindness more common in males than females?

Men have only one X chromosome (so one recessive allele causes the trait)

What happens to alleles during the process of independent assortment?

Alleles are separated individually from each other

During which phase do tetrads form?

Meiosis I (specifically Prophase I)

During which phase do tetrads form?

Meiosis I (specifically Prophase I)

During which phase does chromatin begin to coil into visible chromosomes?

Prophase

What is the relationship between diploid and haploid chromosome numbers?

Haploid (n) is half the diploid (2n) number; in humans, diploid = 46 and haploid = 23

In polygenic inheritance, what is true about the relationship between genes and traits?

More than one gene is involved in the expression of a trait

What structure does a duplicated chromosome consist of before cell division begins?

Two identical chromatids

During which phase do chromosomes exchange genes during crossing over?

Meiosis I (specifically Prophase I)

Is genetics the study of heredity and the passing of traits from one generation to another?

True

What is the purpose of meiosis in terms of cell production?

To form haploid gametes (sex cells)

During which phase does cytoplasm divide among new cells?

Cytokinesis (occurs after telophase in both mitosis and meiosis)

What are Mendel's three principles of genetics?

Principle of Heredity (traits are passed via factors/genes), Principle of Segregation (alleles separate during gamete formation), and Principle of Independent Assortment (genes for different traits segregate independently)

During which phase is DNA replicated?

Interphase (specifically S phase)

Is the combination of alleles that constitute an organism's genetic makeup the organism's phenotype?

False (that describes the genotype; phenotype is the physical expression)

Do promoters, enhancers, and silencers tell RNA polymerase where to start copying RNA and whether genes should be turned on or off?

True

How is a cell with only one complete set of chromosomes described?

Haploid

Before mitosis begins, what does a chromosome consist of?

Two chromatids attached by a centromere

What type of genes control the development of specialized cells in embryos?

Homeotic genes

Why are sex-linked traits more common in males?

Males have only one X chromosome, so a single recessive allele on X causes the trait; females need two recessive alleles (one on each X)

During which phase do individual chromosomes align along the equatorial plane?

Meiosis II (specifically Metaphase II)

How do enhancers and silencers regulate gene expression?

Enhancers increase transcription by binding to promoters (like a gas pedal); silencers decrease transcription by blocking RNA polymerase (like a brake)

In snapdragons with incomplete dominance (red, white, or pink flowers), can a cross of two non-red snapdragons produce red snapdragons?

No (two pink (RW) or two white (WW) cannot produce red (RR); would need at least one red parent)

What genetic tool shows the expression of a hereditary trait across multiple generations?

Pedigree

Do genes consist of chromosomes coiled around histones?

False (chromosomes consist of DNA coiled around histones; genes are segments of DNA)

During which phase does the nucleus begin to re-form?

Telophase

How do dominant and recessive alleles differ in expression?

Dominant alleles are expressed when present (even with one copy); recessive alleles require two copies to be expressed

When an animal with white fur is crossed with an animal with red fur and offspring show both white and red hairs, is this codominance?

True

Is most of a cell's life spent undergoing mitosis?

False (most time is spent in interphase)

In humans, are sex chromosomes known as either X or Y chromosomes?

True

During which phase of meiosis are homologous pairs separated and pulled apart by the spindle?

Meiosis I (specifically Anaphase I)

The TATA box is a common kind of what DNA sequence?

Promoter

What process do cells undergo to change and perform specific tasks?

Cell differentiation

How does crossing over during meiosis contribute to genetic diversity?

Homologous chromosomes exchange genetic material, creating new allele combinations not found in either parent

During which phase do chromosomes uncoil and cytokinesis begin?

Telophase

In the chin cleft problem (C dominant over c), what is the probability a heterozygous cleft-chinned man and uncleft-chinned woman will have a cleft-chinned child?

50% or 1/2 (Cc × cc produces 1/2 Cc and 1/2 cc)

During which phase do chromosomes align along the equatorial plane?

Metaphase

What's the difference between genotype and phenotype?

Genotype is the genetic makeup (allele combination); phenotype is the physical expression of those alleles

If an organism is heterozygous for a gene T with tall (T) and short (t) alleles showing simple dominance, will the organism be tall?

rue (the dominant allele T determines the phenotype)

During which phase of mitosis is the mitotic spindle assembled?

Prophase