Biology test 4 part 2

Once they are produced, sperm move to the _____, where they mature and are stored.

epididymis

The ovarian cycle is divided into two phases. During the _____ phase, the follicles undergo development and during the _____ phase, the corpus luteum prepares the uterus for implantation.

follicular; luteal

The HIV protein that is involved in attachment of the virus to host cells is

gp120.

Oxygen is transported mostly by _____, while carbon dioxide is transported mostly by _____.

hemoglobin; the cytoplasm of RBCs

The steroid hormone-receptor complex binds to

hormone response elements in DNA.

Dehydration is detected by osmoreceptors in the

hypothalamus.

Consuming B vitamins in excess of need will

increase B vitamins in urine.

As the cycle progresses and secondary follicles develop, the blood concentrations of estrogen and progesterone

increase.

The drug AZT

inhibits the enzyme reverse transcriptase.

Which of the following statements about thyroxine is TRUE?

it is water-insoluble and lipophilic

The concentric rings of bone, which make up a new osteon, are called

lamellae.

The thyroid gland secretes

large amounts of tetraiodothyronine and small amounts of triiodothyronine.

Which organ produces bile?

liver

Enzymes assist in the occurrence of reactions by

lowering of activation energy.

Ovulation is triggered when the anterior pituitary releases _____.

luteinizing hormone

The type of cells infected by HIV are ________ early in the course of an infection and ________ late in the infection.

macrophages ; helper T cells

How often can a sucrase molecule be used to hydrolyze sucrose?

many times

Which of the following has an antrum?

mature follicle

Which of the following is involved in ovulation?

mature follicle

After the secondary follicle develops into a vesicular follicle, it undergoes _____, producing a haploid secondary oocyte and a haploid polar body.

meiosis

The HIV enzyme that makes a double-stranded DNA copy of the viral genome is

reverse transcriptase.

The muscle fibers within muscle cells are divided into myofibrils, which are further divided into _____, the contractile units of muscles.

sarcomeres

When a primary follicle enlarges, and there are several layers of granulosa cells, it is called a

secondary follicle.

Which stage between germ cells and mature sperm is the first haploid stage?

secondary spermatocyte

Spermatogenesis occurs in the

seminiferous tubules.

During the overall process of muscle contractions, the sarcomeres _____ as they slide the actin filaments past the myosin filaments.

shorten

Most nutrient absorption occurs in the

small intestine.

The sodium-potassium pump functions to pump

sodium ions out of the cell and potassium ions into the cell.

Which of the following is a correct sequence of cells in spermatogenesis?

spermatogonium → primary spermatocyte → secondary spermatocyte

The mode of action of steroid hormones involves

stimulation of mRNA transcription.

Hydrochloric acid is secreted in the

stomach

Once oxygenated, red blood cells (RBCs) travel to the rest of the body through the _____.

systemic circuit of the circulatory system

During muscle contraction

the A band remains the same and the I band narrows.

Which of the following statements about H zones and I bands is TRUE?

the H zones contain only myosin, while the I bands contain only actin

Because the partial pressure of the oxygen in red blood cells (RBCs) within the capillaries is lower than the partial pressure of oxygen in the alveolus, oxygen diffuses from

the alveolus into the capillaries and then into the RBCs.

Internal respiration refers to the exchange of gases between _____, while external respiration refers to the exchange of gases between _____.

the blood and tissues of our bodies; the atmosphere and our lungs

Which of the following statements about the resting membrane potential is TRUE?

the exterior of the cell has a net positive charge and the interior has a net negative charge

Which of the following stages of gastric secretion is characterized by distention of the stomach walls?

the gastric phase

Complete the following sentence. During an action potential,

the gates of the sodium channels open first and sodium ions flow down their concentration gradients to the inside of the cell. The gates of the potassium channels open second and potassium ions flow down their concentration gradients to the outside of the axon.

What function do many B vitamins serve in the production of energy?

they function as co-enzymes

In the example shown, what co-enzyme is used to assist in the production of ATP from pyruvate?

thiamine pyrophosphate

An action potential arriving at the presynaptic terminal causes

voltage-gated calcium ion channels to open, and calcium ions to diffuse into the cell.

Which molecule is responsible for the separation of sucrose into its componenets?

water

Depolarization occurs because

more Na+ diffuse into the cell than K+ diffuse out of it.

Which of the following is the correct order for the major parts of the gastrointestinal tract?

mouth, esophagus, stomach, small intestine, large intestine

During one cycle, the sodium-potassium pump binds and moves.

3 Na+ and 2 K+.

At which of the following ages would calcium loss from bone be more than calcium deposits into bone, even when a high calcium diet is eaten?

50 years old

Once the peptide hormone is bound to the receptor, an enzymatic reaction is started. What is the immediate culmination of this enzymatic reaction?

ATP is converted to cyclic AMP or cAMP.

Once neurotransmitters flow into the synaptic cleft between two neurons,

All of the answer choices are correct.

Which of the following is NOT a benefit of using chemical signals rather than electrical signals to send messages to the next neuron?

All of the answer choices are correct.

Which of the following is true regarding the action potential of a neuron?

All of the answer choices are correct.

Which of the following is NOT a function of the kidneys?

Assist in the exchange of oxygen and carbon dioxide gases in the blood

Which of the following statements about thyroxine is TRUE? p2

Both the T3 and T4 forms enter target cells.

An antiviral factor called ________ has been found in ________ cells.

CAF ; CD8

What is the overall goal of epinephrine when released into the body?

Epinephrine is a protein hormone and activates the flight-or-fight response and helps generate ATP that will be used for muscle contraction.

Binding of a signal molecule to a cell surface receptor activates a ________, which in turn ________.

G-protein ; stimulates an enzyme to produce a second messenger

In the case of epinephrine, the enzyme cascade created by cAMP causes a chemical reaction to occur. Which of the following choices best describes that chemical reaction?

Glycogen is broken down into glucose, which is used to make ATP for muscle contractions.

Which choice correctly pairs each part of the sperm to its description?

Head- has an acrosome Middle piece- contains mitochondria Tail- a flagellum that propels the sperm

Where is sucrase found in the human body?

on the microvilli of the small intestine

How does sucrose change the configuration of sucrase?

It binds to the active site.

Peptide hormones are specific for receptors located

on the surface of the cell.

Immediately after the cross-bridge is formed and ADP and phosphate are released, what happens to the actin filament?

It is pulled closer towards the center of the sarcomere, causing muscle contraction.

Acetylcholine has which effect on the post-synaptic neuron?

Ligand gated sodium ion channels open and sodium diffuses in.

During depolarization, which of the following statements about voltage-gated ion channels is TRUE?

Na+ gates open before K+ gates

The bone producing cells, which deposit an extracellular matrix, are called

osteoblasts.

Which of the following is the best description of the difference between normal, fully developed bone and osteoporotic bone?

Osteoporotic bone has much larger spaces in its bone structure and is weaker than normal bone.

The combination of all of the concentric rings of bone built around a single blood vessel is called a(n)

osteon

Peptide hormones work very quickly within the cell. Which of the following reasons describes why peptide hormones are able to work so quickly?

Peptide hormones make use of second messengers, which initiate enzyme cascades. These allow the cell to respond rapidly to the initial signal.

Involuntary muscle contractions, which move a bolus through the gastrointestinal tract are called

peristalsis.

During tubular secretion, certain molecules are actively secreted from the _____ into the _____ for excretion.

peritubular capillary network; convoluted tubules

Antidiuretic hormone (ADH) is released by the

posterior pituitary.

Steroid hormones bind to

protein receptors in the cytoplasm or nucleus of the target cell.

The targets of steroid hormones tend to be

protein receptors, either in the cytoplasm or within the nucleus.

Why are steroid hormones slower to function then peptide hormones?

Steroid hormones do not use second messengers, but instead, must wait for gene expression pathways to be activated.

What is responsible for the start of the ovarian cycle?

The anterior pituitary releases FSH that stimulates the ovary to release estrogen. This estrogen signals the start of the ovarian cycle.

During a resting potential, which of the following situations is true?

The axon is not conducting an impulse and the inside of the axon is negative compared to the outside of the axon.

What is the overall purpose of tubular reabsorption, the second stage of urine formation?

The body distinguishes between important nutrients, such as glucose and amino acids, from waste products destined for excretion, such as salts.

Which statement best explains the effects of phosphorylation of proteins via second messenger pathways?

The effects depend on the identity of the cell and the proteins that are phosphorylated.

When calcium ions are released into muscle fibers, what happens along the actin filament?

The position of the tropomyosin threads shift, exposing myosin binding sites, allowing the myosin head to attach to the actin filament.

The concentration of sodium ions is greater outside the axon than inside the axon during the resting potential. Why is that the case?

The sodium-potassium pumps actively transport sodium ions outside of the cell.

Synaptic vesicles contain chemicals called neurotransmitters. What is the function of these neurotransmitters?

They act as chemical signals that relay information between neurons.

Steroid hormones are lipid soluble. What implications does this have in terms of how they enter cells?

They are able to easily diffuse across the cell membrane and do not require the aid of receptors.

What process is first initiated after the steroid hormone binds to the receptor within the nucleus of a cell?

Transcription of specific genes

Why is glomerular filtrate forced from the capillaries to the glomerular capsule?

Two of these choices are correct: because it is under high pressure as it is pumped through the renal arteries AND because the diameter of the capillary is decreased, increasing the pressure.

Where does glomerular filtration, the first stage of urine formation, occur?

Within the glomerular capsule of the kidney nephrons

The primary neurotransmitter at the neuromuscular junction is

acetylcholine.

Acetylcholine is broken down into acetic acid and choline by the enzyme

acetylcholinesterase.

Muscle contraction is caused by

actin filaments sliding past myosin filaments.

Absolute refractory period causes

action potential propagation to occur in one direction.

The second messenger cAMP is synthesized by the enzyme

adenylyl cyclase.

Insulin

allows cells to take in glucose.

Why does bone loss become an issue after age 30?

because the process of bone remodeling slows as the loss of calcium deposits exceeds its replacement

Chemokines appear to inhibit HIV infection by

blocking the CXCR4 and CCR5 coreceptors.

What is the source of energy used to power the sodium-potassium pump?

breakdown of ATP

In simple terms, sucrase

breaks sucrose into glucose and fructose.

Which of these minerals is a recommended supplement for women, in attempts to maintain strong bones?

calcium

An action potential

causes the inside of the neuron cell membrane to become positively charged in reference to the outside.

Which of the following inhibits the secretion of the gastric glands?

chyme pH of less than 2 due to HCl or lipids

ADH functions to

decrease urine volume output and cause blood vessel constriction.

An action potential generates local currents that tend to _____ the membrane immediately adjacent to the action potential.

depolarize

In the neuromuscular junction, acetylcholine

diffuses across the synaptic cleft and binds to acetylcholine receptors on the postsynaptic muscle fiber.

Individuals with type I diabetes

do not produce insulin.

Individuals with type II diabetes

do not respond to insulin.

Within a neuron, information is transmitted down the length of a single axon through

electrical signals called action potentials.