Hi are there any biology experts available

Customer Question

Hi are there any biology experts available?

Optional Information:
Level: college; Subject: biology

Submitted: 1427 days and 7 hours ago.

Category: Homework

Value: $15

Status: CLOSED

Expert: asciandwildlifebio replied 1426 days and 20 hours ago.

Hello lekpeh, please post your question.

Customer replied 1426 days and 18 hours ago.

Hi,

Thanks for taking my question.

I would like to know when you are online, so we can work together, because 10 hrs and 36 minutes later is a little too late for the question I had, however, I would like to be online when you are on.

Thanks, XXXXX XXXXX look forward to working with you.

Expert: asciandwildlifebio replied 1426 days and 17 hours ago.

Lekpeh, I am online as much as I can be. If you post your question, an expert will get to it as soon as possible. If you would like me to answer it you can always request me, or put my username in the title of your question. I look forward to working with you. And, just as a heads-up I will be away this weekend. Also, it's best to post upcoming assignments ahead of time so experts can double check details of the assignment and be as complete and comprehensive as possible.

Customer replied 1426 days and 8 hours ago.

Hi asciandwildlifebio,

are you available to help me please?

Expert: Andrea replied 1425 days and 18 hours ago.

HelloCustomer

I am a biology expert and I can help you, if you'd like. Asciandwildlifebio opted out of this question, so she has allowed other experts to help you.

I am not available this weekend, but I can be online on Monday morning around 9:30am or in the afternoon around 3pm, depending on which you prefer. If you need help sooner, I can opt out and allow another expert to help you.

You could also post your question and let me know when you need the answer by, which would allow me to start working on the question if you are not online. It's up to you!

Thanks!

AndreaSBP

Customer replied 1400 days and 10 hours ago.

Part A

Which of the following is a function of meiosis but not mitosis in eukaryotes? (Concept 12.1)

Hint A.1
*Hint not displayed*

ANSWER:

repair of damaged organs

cell replacement

asexual reproduction

production of animal gametes

growth

Answer not displayed

Part B

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? (Concept 12.1)

Hint B.1
*Hint not displayed*

ANSWER:

23

46

92

23 or 46, depending on the portion of prophase examined

46 or 92, depending on the portion of prophase examined

Answer not displayed

Part C

It is difficult to observe individual chromosomes with a light microscope during interphase because _____. (Concept 12.1)

Hint C.1
*Hint not displayed*

ANSWER:

they have uncoiled to form long, thin strands

the DNA has not been replicated yet

sister chromatids do not pair up until division starts

the spindle must move them to the metaphase plate before they become visible

they leave the nucleus and are dispersed to other parts of the cell

Answer not displayed

Part D

The kinetochores _____. (Concept 12.2)

Hint D.1
*Hint not displayed*

ANSWER:

attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow

are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers

of each spindle interdigitate at the cell's equator and then move apart, causing the cell to elongate

are sites at which microtubules attach to chromosomes

are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis

Answer not displayed

Part E

Which of the following correctly matches a phase of the cell cycle with its description? (Concept 12.2)

Hint E.1
*Hint not displayed*

ANSWER:

G₂: cell division

G₁: follows cell division

M: duplication of DNA

S: immediately precedes cell division

All of the above are correctly matched.

Answer not displayed

Part F

In some organisms such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this? (Concept 12.2)

Hint F.1
*Hint not displayed*

ANSWER:

a decrease in chromosome number

large cells containing many nuclei

inability to duplicate DNA

a rapid rate of gamete production

division of the organism into many cells, most lacking nuclei

Answer not displayed

Part G

Which of the following is/are difference(s) between the fission of a bacterium and mitosis in human cells? (Concept 12.2)

Hint G.1
*Hint not displayed*

ANSWER:

Bacteria are smaller and simpler than human cells.

A bacterium has only one chromosome, human chromosomes are paired.

Human chromosomes are larger and more complex.

Duplicated bacterial chromosomes attach to the plasma membrane. Duplicated human chromosomes are attached to each other.

All of the above are differences between the fission of a bacterium and human cell division.

Answer not displayed

Part H

Cytochalasin B is a chemical that disrupts microfilament formation. This chemical would interfere with _____. (Concept 12.2)

Hint H.1
*Hint not displayed*

ANSWER:

cleavage

binary fission

formation of the mitotic spindle

formation of the cell plate

DNA replication

Answer not displayed

Part I

Cells will usually divide if they receive the proper signal at a checkpoint in the _____ phase of the cell cycle. (Concept 12.3)

Hint I.1
*Hint not displayed*

ANSWER:

cytokinesis

S

G₁

G₂

M

Answer not displayed

Part J

A benign tumor, but not a malignant tumor, is one in which the cancerous cells _____. (Concept 12.3)

Hint J.1
*Hint not displayed*

ANSWER:

have an unusual number of chromosomes

migrate from the initial site of transformation to other organs or tissues

remain confined to their original site

are the result of the transformation of normal cells

can divide indefinitely if an adequate supply of nutrients is available

Answer not displayed

Score Summary: Your score on this assignment is 0%.
You received 0 out of a possible total of 10 points.

Customer replied 1400 days and 10 hours ago.

Hi Andrea,

I have 50 questions, and I need the answers by mid night on friday 7/6/09.

Please let me know if you have time to complete them or not.

I just sent you the first 10 of the 50.

I am going to send 10 at a time cuz that is all I am able to post.

Also, please let me know if you are able to view them or not.

Thanks

Customer replied 1400 days and 10 hours ago.

sorry. I meant monday 7/6/09

here is the second set, the third, fourth, and fifth will follow, please watch for them.

Part A

Asexual reproduction _____. (Concept 13.1)

Hint A.1
*Hint not displayed*

ANSWER:

is limited to plants

requires both meiosis and mitosis

produces offspring genetically identical to the parent

leads to a loss of genetic material

is limited to single-cell organisms

Answer not displayed

Part B

A human somatic cell contains _____. (Concept 13.1)

Hint B.1
*Hint not displayed*

ANSWER:

45 autosomes and 1 sex chromosome

44 autosomes and 2 sex chromosomes

22 autosomes and 1 sex chromosome

n chromosomes

21 autosomes and 2 sex chromosomes

Answer not displayed

Part C

For what purpose might a karyotype be prepared? (Concept 13.2)

Hint C.1
*Hint not displayed*

ANSWER:

for prenatal screening, to determine if a fetus has the correct number of chromosomes

to determine whether a fetus is male or female

to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations

The first and second answers are correct.

The first three answers are correct.

Answer not displayed

Part D

In alternation of generations, the diploid stage of a plant that follows fertilization is the _____. (Concept 13.2)

Hint D.1
*Hint not displayed*

ANSWER:

gametophyte

chiasmata

sporophyte

spore

karyotype

Answer not displayed

Part E

How are sister chromatids and homologous chromosomes different from each other? (Concepts 13.2 and 13.3)

Hint E.1
*Hint not displayed*

ANSWER:

They are not different. Homologous chromosomes and sister chromatids are both identical copies of 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.

Homologous chromosomes are identical copies of each other. One sister chromatid comes from the father, and one comes from the mother.

Sister chromatids are only formed during mitosis. Homologous chromosomes are formed during meiosis.

Homologous chromosomes are closely associated with each other in both mitosis and meiosis. Sister chromatids are only associated with each other during mitosis.

Answer not displayed

Part F

Mitosis results in the formation of _____; meiosis results in the formation of _____. (Concept 13.3)

Hint F.1
*Hint not displayed*

ANSWER:

two diploid cells ... two diploid cells

two diploid cells ... four haploid cells

four haploid cells ... two diploid cells

two diploid cells ... two haploid cells

four diploid cells ... four haploid cells

Answer not displayed

Part G

Which of the following occurs during meiosis but not during mitosis? (Concept 13.3)

Hint G.1
*Hint not displayed*

ANSWER:

A spindle apparatus forms.

Synapsis occurs.

Chromosomes migrate to opposite poles.

Chromosomes condense.

Chromosomes align at the metaphase plate.

Answer not displayed

Part H

Crossing over is _____. (Concept 13.3)

Hint H.1
*Hint not displayed*

ANSWER:

also referred to as the "independent assortment of chromosomes"

a direct consequence of the separation of sister chromatids

the movement of genetic material from one chromosome to a nonhomologous chromosome

making an RNA copy of a DNA strand

the exchange of homologous portions of nonsister chromatids

Answer not displayed

Part I

Genetic variation occurs when chromosomes are shuffled in _____ and fertilization. (Concept 13.4)

Hint I.1
*Hint not displayed*

ANSWER:

genetic drift

meiosis

mitosis

natural selection

mutation

Answer not displayed

Part J

Heritable variation is required for _____. (Concept 13.4)

Hint J.1
*Hint not displayed*

ANSWER:

evolution

meiosis

asexual reproduction

the production of a clone

mitosis

Answer not displayed

Score Summary: Your score on this assignment is 0%.
You received 0 out of a possible total of 10 points.

Customer replied 1400 days and 10 hours ago.

Part A

In his breeding experiments, Mendel first crossed true-breeding _____ generation plants to produce the _____ generation, which were then allowed to self-pollinate to generate the _____ offspring. (Concept 14.1)

Hint A.1
*Hint not displayed*

ANSWER:

P₁ ... P₂ ... F

P₁ ... P₂ ... P₃

F ... P₁ ... P₂

F₁ ... F₂ ... F₃

P ... F₁ ... F₂

Answer not displayed

Part B

A plant with the genotype AABbcc _____. (Concept 14.1)

Hint B.1
*Hint not displayed*

ANSWER:

Will not express the recessive c allele.

is heterozygous at two loci

is triploid

has recessive alleles at three loci

is homozygous at two loci

Answer not displayed

Part C

An allele is _____. (Concept 14.1)

Hint C.1
*Hint not displayed*

ANSWER:

the dominant form of a gene

the recessive form of a gene

an alternative version of a gene

a type of chromosome

a variety of pea plant used by Mendel

Answer not displayed

Part D

GgTt pea plants can produce _____ type(s) of gametes, but a ggtt plant can produce _____ type(s) of gametes. (Concept 14.2)

Hint D.1
*Hint not displayed*

ANSWER:

one ... one

four ... two

four ... one

one ... two

two... one

Answer not displayed

Part E

Two organisms with genotype AaBbCcDdEE mate. These loci are all independent. What fraction of the offspring will have the same genotype as the parents? (Concept 14.2)

Hint E.1
*Hint not displayed*

ANSWER:

3/4

1/4

4/3

1/16

9/64

Answer not displayed

Part F

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F₁ are pink. What does this say about the alleles for the parental traits? (Concept 14.3)

Hint F.1
*Hint not displayed*

ANSWER:

Red and white are codominant.

Red shows incomplete dominance over white.

Red is completely dominant.

Both red and white are pleiotropic.

Pink is dominant, while red and white are recessive.

Answer not displayed

Part G

Height in humans generally shows a normal (bell-shaped) distribution. What type of inheritance most likely determines height? (Concept 14.3)

Hint G.1
*Hint not displayed*

ANSWER:

A combination of epistasis and environmental factors.

A combination of multiple alleles and codominance

incomplete dominance

A combination of complete dominance and environmental factors.

A combination of polygenic inheritance and environmental factors.

Answer not displayed

Part H

Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true? (Concept 14.4)

Hint H.1
*Hint not displayed*

ANSWER:

His daughters will die of Huntington's disease but not his sons.

At least one of Woody Guthrie's parents must also have had the allele for Huntington's disease.

All of his children will develop Huntington's disease.

His sons will develop Huntington's disease but not his daughters.

There is not enough information to answer the question.

Answer not displayed

Part I

Various procedures can be used to detect genetic disorders before birth. Among the tests discussed in this chapter, _____ is the least invasive, while _____ and _____ allow the chromosomes of the fetus to be examined. (Concept 14.4)

Hint I.1
*Hint not displayed*

ANSWER:

amniocentesis ... fetoscopy ... chorionic villus sampling

ultrasound imaging ... fetoscopy... amniocentesis

amniocentesis ... ultrasound imaging ... chorionic villus sampling

ultrasound imaging ... chorionic villus sampling ... amniocentesis

chorionic villus sampling ... fetoscopy ... amniocentesis

Answer not displayed

Part J

If an individual is heterozygous for the sickle-cell trait _____. (Concept 14.4)

Hint J.1
*Hint not displayed*

ANSWER:

he or she will show no symptoms of the disease because the allele that causes sickle-cell disease is recessive

he or she will not develop full-blown sickle-cell disease but may show symptoms under certain circumstances

he or she will have full-blown sickle-cell disease because the allele is dominant

he or she will be more apt to acquire a serious case of malaria

none of the above

Answer not displayed

Score Summary: Your score on this assignment is 0%.
You received 0 out of a possible total of 10 points.

Customer replied 1400 days and 10 hours ago.

Part A

Mendel's Principle of Segregation can be visualized when we observe _____. (Concept 15.1)

Hint A.1
*Hint not displayed*

ANSWER:

Sister chromatids separating during mitosis.

Homologous chromosomes separating during Meiosis I.

The behavior of sex-linked genes.

Homologous chromosomes separating during Meiosis II.

The replication of DNA.

Answer not displayed

Part B

The most common phenotype in a natural population is referred to as the _____. (Concept 15.1)

Hint B.1
*Hint not displayed*

ANSWER:

mutant phenotype

wild type

autosome

genotype

locus

Answer not displayed

Part C

A white-eyed female Drosophila is crossed with a red-eyed male Drosophila. Which statement below correctly describes the results? (Concept 15.1)

Hint C.1
*Hint not displayed*

ANSWER:

Twenty-five percent of the females will have white eyes.

None of the females will have red eyes.

None of the females will have white eyes.

Twenty-five percent of the females will have red eyes.

Fifty percent of the females will have red eyes.

Answer not displayed

Part D

In humans, the _____ determines the sex of the offspring because _____. (Concept 15.2)

Hint D.1
*Hint not displayed*

ANSWER:

female gamete ... only the female gametes can have one of two functional sex chromosomes

male ... the sperm can fertilize either a female egg or a male egg

male gamete ... each male gamete can contribute either an X or a Y chromosome

female gamete ... only the female gamete provides cytoplasm to the zygote

chromosome contribution from both parents ... the offspring uses all the parents' chromosomes

Answer not displayed

Part E

In general, the frequency with which crossing over occurs between two linked genes depends on _____. (Concept 15.3)

Hint E.1
*Hint not displayed*

ANSWER:

whether the genes are on the X or some other chromosome

how far apart they are on the chromosome

whether the genes are dominant or recessive

the characters the genes code for

the phase of meiosis in which the crossing over occurs

Answer not displayed

Part F

How many map units is a recombination frequency of 5% equal to? (Concept 15.3)

Hint F.1
*Hint not displayed*

ANSWER:

5 centimorgans

5 centisturtevants

5%

10 centimorgans

2.5 centimorgans

Answer not displayed

Part G

A situation in which chromosome number can be represented as either 2n+1 or 2n-1 is called_____. (Concept 15.4)

Hint G.1
*Hint not displayed*

ANSWER:

Methylation.

Gene linkage.

inversion.

Polyploidy.

aneuploidy

Answer not displayed

Part H

If a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction, the resulting chromosomal abnormality is called _____. (Concept 15.4)

Hint H.1
*Hint not displayed*

ANSWER:

a deletion

a translocation

polyploidy

a nondisjunction

an inversion

Answer not displayed

Part I

A particular allele will either be expressed or silenced, depending on whether it is inherited from a male rather than a female. This phenomenon is known as _____. (Concept 15.5)

Hint I.1
*Hint not displayed*

ANSWER:

aneuploidy

polyploidy

genomic imprinting

extranuclear inheritance

sex linkage

Answer not displayed

Part J

Human mitochondria _____. (Concept 15.5)

Hint J.1
*Hint not displayed*

ANSWER:

have linear DNA

are inherited as an X-linked trait

are all inherited from the father

are all inherited from the mother

do not contain DNA

Answer not displayed

Score Summary: Your score on this assignment is 0%.
You received 0 out of a possible total of 10 points.

Customer replied 1400 days and 10 hours ago.

Part A

Griffith's experiments with S. pneumoniae were significant not only because they showed that traits could be transferred from one organism to another, but because they showed that _____. (Concept 16.1)

Hint A.1
*Hint not displayed*

ANSWER:

Heat kills bacteria.

A virus made the bacteria pathogenic.

DNA was the genetic material.

Protein could not be the genetic material.

The transferred traits were heritable.

Answer not displayed

Part B

In the Hershey and Chase experiment that helped confirm that DNA, not protein, was the hereditary material, the key finding was that _____. (Concept 16.1)

Hint B.1
*Hint not displayed*

ANSWER:

radioactively labeled sulfur was present inside the infected bacteria

radioactively labeled phosphorus was present inside the infected bacteria

radioactively labeled carbon was present inside the infected bacteria

radioactively labeled sulfur was found outside of the infected bacteria

radioactively labeled phosphorus was found outside of the infected bacteria

Answer not displayed

Part C

The X-ray diffraction studies conducted by _____ were key to the discovery of the structure of DNA. (Concept 16.1)

Hint C.1
*Hint not displayed*

ANSWER:

Griffith

McClintock

Meselson and Stahl

Franklin

Chargaff

Answer not displayed

Part D

DNA replication is said to be semiconservative. This means that _____. (Concept 16.2)

Hint D.1
*Hint not displayed*

ANSWER:

one of the two resulting double helices is made of two old strands, and the other is made of two new strands

the old double helix is degraded and half of its nucleotides are used in the construction of two new double helices

half of the old strand is degraded and half is used as a template for the replication of a new strand

each new double helix consists of one old and one new strand

one strand of the new double helix is made of DNA and the other strand is made of RNA

Answer not displayed

Part E

What is the function of helicase in DNA replication? (Concept 16.2)

Hint E.1
*Hint not displayed*

ANSWER:

It relieves strain from twisting of the double helix as it is unwound.

It adds nucleotides to the new strand in the 5' to 3' direction.

It joins together Okazaki fragments.

It checks for errors in the newly synthesized DNA strand.

It untwists the double helix and separates the two DNA strands.

Answer not displayed

Part F

_____ fixes mistakes made during DNA replication; _____ repairs damage to a preexisting double helix. (Concept 16.2)

Hint F.1
*Hint not displayed*

ANSWER:

The leading strand ... the lagging strand

Mismatch repair ... nucleotide excision repair

Operon repair ... histone repair

Proto-oncogene repair ... oncogene

Transformation ... transduction

Answer not displayed

Part G

In nucleotide excision repair, damaged DNA is excised by _____. (Concept 16.2)

Hint G.1
*Hint not displayed*

ANSWER:

nuclease

restriction enzymes

helicase

ligase

primase

Answer not displayed

Part H

The repetitive DNA sequences present at the ends of eukaryotic chromosomes are called _____. (Concept 16.2)

Hint H.1
*Hint not displayed*

ANSWER:

telomeres

chromomeres

centromeres

sarcomeres

polypeptides

Answer not displayed

Part I

Chromosomes are made up of _______ (Concept 16.3)

Hint I.1
*Hint not displayed*

ANSWER:

DNA and euchromatin.

DNA, RNA, and proteins.

DNA, heterochromatin, and histone proteins.

DNA and proteins.

DNA.

Answer not displayed

Part J

During interphase DNA is in the form of ______ and is ______. (Concept 16.3)

Hint J.1
*Hint not displayed*

ANSWER:

Chromatin; less condensed than mitotic chromosomes.

Highly condensed chromosomes; unavailable for gene expression.

Chromatin; unavailable for gene expression.

Highly condensed chromosomes; called heterochromatin.

Chromatin; completely uncoiled and loose.

Answer not displayed

Score Summary: Your score on this assignment is 0%.
You received 0 out of a possible total of 10 points.

Expert: Andrea replied 1400 days ago.

HelloCustomer

I can do this for you, no problem! I'll get started right away.

Thanks!

Andrea

Customer replied 1399 days and 21 hours ago.

Thanks for taking my problems, I really appreciate it.

I will keep checking in.

Thanks

Accepted Answer

Expert: Andrea replied 1399 days and 16 hours ago.

THIS ANSWER IS LOCKED!
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Expert Type	Graduate Student
Category:	Homework
Pos. Feedback:	100.0 %
Accepts:	136
Answered:	7/1/2009

Experience: Doctoral Candidate and Adjunct Prof. of Biology

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Customer replied 1399 days and 15 hours ago.

Thanks so much Andrea.

I am going to accept, and appreciate your help.

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