Ask Question, Ask an Expert

+1-415-315-9853

info@mywordsolution.com

Ask Biology Expert

1. The stimulus for secretion of neurotransmitters into the synaptic cleft is an increase in
A) sodium levels.
B) calcium levels.
C) neurotransmitter levels.
D) chloride levels.
E) potassium levels.

2. Multiple sclerosis is a result of
A) the absence of myelin on nerve cells.
B) having excess acetylcholine receptors.
C) blocking the nodes on Ranvier.
D) excess amounts of myelin on nerve cells.
E) an immune system attack on nerve fibers.

3. Name for the phase at the end of an action potential when the membrane potential becomes more negative than it is at rest is the ________ phase.
A) threshold
B) refractory
C) hyperpolarizing
D) depolarizing
E) repolarizing

4. To have a hormone receptor system that is responsive to changes in hormone concentration, it is useful if the concentration of the hormone is
A) far below the Kd before the stimulation of hormone secretion.
B) always more than 10 times the Kd.
C) always constant.
D) never more than 10 times the Kd.
E) far above the Kd before the stimulation of hormone secretion.

5. Desensitization of a cell to a ligand may involve all BUT
A) receptor-mediated endocytosis.
B) destruction of the ligand.
C) lowered affinity of a receptor for the ligand.
D) a lessened response to the ligand.
E) receptor down-regulation.

6. Base your answers to the problems below on the following information:
You have isolated a factor from the blood of a space alien and named it XFF (for X-files factor). Based on preliminary data, you think that XFF could be one of three compounds normally found in human blood: epidermal growth factor (EGF), epinephrine, or estrogen.

You obtain two different preparations of XFF, one of which contains the receptors for XFF. You perform a binding assay and obtain a standard curve. Based upon this data, what value would reflect the affinity of the receptor for the ligand? (Assume a 1 XFF to 1 receptor interaction.)
A) Kd - Bmax
B) Bmax
C) Kd
D) 1/Bmax
E) This information cannot be obtained in this manner.

7. G protein-adenyl cyclase activity has been shown, in some cases, to be associated with certain diseases. In the case of cholera, which of the following is NOT correct?
A) Vibrio cholera bacteria colonize the gut.
B) Cholera toxin is secreted by Vibrio cholera bacteria.
C) Cholera toxin alters Gs so that it no longer hydrolyzes GTP.
D) The toxin, by altering Gs, keeps intracellular cAMP levels high and doesn't allow them to decrease.
E) The cholera toxin causes the cells of the gut to take in salts and fluids.

8. With regard to hormones, responses occurring over the shortest distance would be classified as
A) exocrine.
B) endocrine.
C) paracrine.
D) Choices A, B, and C all act over the same distance.
E) none of the above

9. Kinases and phosphatases are essential in the cell because they
A) are enzymes that destroy damaged proteins.
B) help turn proteins "on and off" through changes in phosphorylation status.
C) sense short poly A tails in mRNA as a signal to degrade the mRNA.
D) destroy second messengers, thereby turning off a signal transduction pathway.
E) all of the above

10. Kinases are enzymes that
A) add phosphate groups.
B) remove phosphate groups.
C) do not alter target activity.
D) are always inhibitory.
E) all of the above.

11. Phosphatases are enzymes that
A) do not alter target activity.
B) remove phosphate groups.
C) add phosphate groups.
D) are always inhibitory.
E) all of the above

12. All of the following are second messengers, EXCEPT
A) inositol trisphosphate.
B) cyclic adenosine monophosphate.
C) diacylglycerol.
D) epinephrine.
E) calcium ions.

Biology, Academics

  • Category:- Biology
  • Reference No.:- M924569

Have any Question? 


Related Questions in Biology

First present the characteristics of water that make it

First present the characteristics of water that make it capable of hydrogen bonding. Then discuss why water is a good solvent and so readily exhibits capillarity. Finally, examine the heat properties of water, specifical ...

State which cells in a human testis produce testosterone

State which cells in a human testis produce testosterone and its function(s) and state which hormones are produced by a human ovary, and their functions.

Determining whether clean groundwater has become dirty and

Determining whether clean groundwater has become dirty and what caused any contamination is a complex pursuit. Stephen Osborn and three colleagues from Duke University set out to learn whether drinking water was really b ...

Briefly describe the changes in lipid composition of

Briefly describe the changes in lipid composition of amniotic fluid before and during fetal lung maturation.

Immune and musculoskeletal diseasesresearch an autoimmune

Immune and Musculoskeletal Diseases Research an autoimmune disease that affects the musculoskeletal system. Write a 2-page paper. Address the following in the paper: The pertinent information on both the immune and muscu ...

1which group of algae appears to be the most closely

1. Which group of algae appears to be the most closely related to the ancestors of true plants? Name one feature that appears to be homologous. 2. What are microphylls and which group of seedless vascular plants are they ...

The a and b loci are 10 cm apart a plant with a genotype

The A and B loci are 10 cM apart. A plant with a genotype aaBB is crossed to plant with a genotype of AAbb. If an F1 plant is self pollinated, what proportion of the progeny will be homozygous dominant or homozygous rece ...

1 much pharmaceutical research targets developing

1. Much pharmaceutical research targets developing anti-cancer drugs that can effectively stimulate the methylation of DNA. Formulate a possible hypothesis to explain why DNA methylation might be an effective anticancer ...

Which part of the human brain is the centre of memory

Which part of the human brain is the centre of memory, learning, thinking and reasoning?

What is the probability of a cross resulting in white

What is the probability of a cross resulting in white offspring when two heterozygous purple pea plants (e.g. Pp x Pp) are bred? What is the genotype for this offspring?

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

Section onea in an atwood machine suppose two objects of

SECTION ONE (a) In an Atwood Machine, suppose two objects of unequal mass are hung vertically over a frictionless

Part 1you work in hr for a company that operates a factory

Part 1: You work in HR for a company that operates a factory manufacturing fiberglass. There are several hundred empl

Details on advanced accounting paperthis paper is intended

DETAILS ON ADVANCED ACCOUNTING PAPER This paper is intended for students to apply the theoretical knowledge around ac

Create a provider database and related reports and queries

Create a provider database and related reports and queries to capture contact information for potential PC component pro

Describe what you learned about the impact of economic

Describe what you learned about the impact of economic, social, and demographic trends affecting the US labor environmen