Bio IB Topic 6.5-6

1.

Which structure is responsible for passing messages directly to effector organs?

A.

A.
B.

B.
C.

C.
D.

D.

Correct Answer
D. D.

Explanation
The axon terminals pass the message on to the dendrites of the next motor neuron through the process of synapses. Motor neutrons send signals from the brain to the muscles.

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2.

After depolorization what happens to restore the resting potential?

A.

Sodium channels open and sodium ions diffuse out of the neuron
B.

Potassium channels open and potassium ions diffuse into the neuron
C.

Potassium channels open and potassium ions diffuse out of the neuron
D.

Sodium channels open and sodium ions diffuse into the neuron

Correct Answer
C. Potassium channels open and potassium ions diffuse out of the neuron

Explanation
Depolarization is a change from negative to positive. After depolarization occurs repolarization begins. Repolarization is the change back from positive to negative. Depolarization is caused by the sodium ion channel opening allowing sodium ions to enter making the inside of the neutron relatively more positive than the outside. Repolarization occurs when the sodium ion channel closes and the potassium ion channel opens allowing the potassium ions to leave the neuron to make it change from positive to negative. After repolarization has come to completion then the resting potential will begin again by the transmission impulse of sodium(3 leave) and potassium(2 enter) ions across the membrane.

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3.

Which cells secrete insulin?

A.

Beta-cells of the pancreas
B.

Cells of the liver
C.

Alpha-cells of the pancreas
D.

Epithelial cells of the intestine

Correct Answer
A. Beta-cells of the pancreas

Explanation
Beta-cell of the pancreas secrete insulin when blood glucose levels reach high levels. Alpha-cell of the pancreas secrete glucagon when blood glucose levels reach low levels.

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4.

Which organ secretes FSH (follicle-stimulating hormone)?

A.

Ovary
B.

Testis
C.

Pituitary gland
D.

Placenta

Correct Answer
C. Pituitary gland

Explanation
The pituitary gland secretes FSH and LH. The ovary secretes estrogen and progesterone. The testis secrete testosterone.

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5.

In the menstrual cycle in humans, which hormone causes the wall of the follicle to develop after ovulation and to secrete more progesterone?

A.

Estrogen
B.

FSH
C.

LH
D.

Oxytocin

Correct Answer
C. LH

Explanation
The menstrual cycle is controlled by positive and negative feedback mechanisms involving ovarian and pituitary glands hormones. High levels of estrogen inhibits secretion FSH (negative feedback) and stimulations LH production. LH rises to a peak toward the end of the follicular phase. This promotes completion of meiosis in oocyte and partial digestion of follicle wall. This promotes secretion of estrogen (positive feedback) and progesterone.

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6.

What is the role of active transport in the transmission of nerve impulses by neurones?

A.

Propagates an action potential by pumping sodium ions across the membrane out of the neurone.
B.

Propagates an action potential by pumping sodium ions across the membrane into the neurone.
C.

Initiates the action potential needed for the transmission of an impulse by pumping calcium ions out of the endoplasmic reticulum.
D.

Establishes the resting potential needed for the transmission of an impulse by pumping sodium and potassium ions across the membrane.

Correct Answer
D. Establishes the resting potential needed for the transmission of an impulse by pumping sodium and potassium ions across the membrane.

Explanation
Active transport plays a crucial role in establishing the resting potential of a neurone, which is necessary for the transmission of nerve impulses. By actively pumping sodium and potassium ions across the membrane, the neuron creates an electrochemical gradient. This gradient allows for the generation of an action potential, which is the basis of nerve impulse transmission. Therefore, the correct answer is that active transport establishes the resting potential needed for the transmission of an impulse by pumping sodium and potassium ions across the membrane.

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7.

What are responsible for the lowering of blood glucose levels? I. Beta-cells in the pancreas II. Insulin molecules III. Alpha-cells in the pancreas

A.

II only
B.

I and II only
C.

II and III only
D.

I, II and III

Correct Answer
B. I and II only

Explanation
Beta-cell of the pancreas secrete insulin when blood glucose levels reach high levels. Alpha-cell of the pancreas secrete glucagon when blood glucose levels reach low levels.

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8.

How can testis tissue be distinguished from ovary tissue, when seen using a light microscope?

A.

Testis tissue has a layer of muscle fibres and ovary tissue does not.
B.

Testis tissue is cooler than ovary tissue.
C.

Testis tissue contains tubules and ovary tissue does not.
D.

Testis tissue contains pain receptors and ovary tissue does not.

Correct Answer
C. Testis tissue contains tubules and ovary tissue does not.

Explanation
The link below will help further explain what this question is talking about.
https://web.duke.edu/histology/DPT/MaleRepro/MaleRepro.html

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9.

The levels of hormones vary during the menstrual cycle in women. Each hormone reaches its maximum level at a different time in the cycle. In what sequence do the hormones reach their maximum level, if the cycle begins at the start of menstruation?

A.

LH, progesterone, FSH, estrogen
B.

FSH, progesterone, LH, estrogen
C.

LH, estrogen, FSH, progesterone
D.

FSH, estrogen, LH, progesterone

Correct Answer
D. FSH, estrogen, LH, progesterone

Explanation
The link below will talk you through the cycle.
https://www.youtube.com/watch?v=EyvlrjLlpdc

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10.

How is in vitro fertilization different from natural fertilization in humans?

A.

In vitro fertilization involves artificial injection of sperm into the uterus
B.

In vitro fertilization only involves one parent
C.

In vitro fertilization happens outside the body
D.

In vitro fertilization uses stem cells instead of eggs

Correct Answer
C. In vitro fertilization happens outside the body

Explanation
The link below will illustrate the process of in vitro fertilization.
https://www.youtube.com/watch?v=GeigYib39Rs

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