Bio IB Topic 6.5-6

1. Which cells secrete insulin?

Beta-cells of the pancreas

Cells of the liver

Alpha-cells of the pancreas

Epithelial cells of the intestine

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.

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.

2. Which organ secretes FSH (follicle-stimulating hormone)?

Ovary

Testis

Pituitary gland

Placenta

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

Explanation

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

3. 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

II only

I and II only

II and III only

I, II and III

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.

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.

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

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

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

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

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

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.

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.

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

In vitro fertilization involves artificial injection of sperm into the uterus

In vitro fertilization only involves one parent

In vitro fertilization happens outside the body

In vitro fertilization uses stem cells instead of eggs

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

Explanation

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

6. 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?

LH, progesterone, FSH, estrogen

FSH, progesterone, LH, estrogen

LH, estrogen, FSH, progesterone

FSH, estrogen, LH, progesterone

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

Explanation

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

7. After depolorization what happens to restore the resting potential?

Sodium channels open and sodium ions diffuse out of the neuron

Potassium channels open and potassium ions diffuse into the neuron

Potassium channels open and potassium ions diffuse out of the neuron

Sodium channels open and sodium ions diffuse into the neuron

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.

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.

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

A.

B.

C.

D.

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.

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.

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

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

Testis tissue is cooler than ovary tissue.

Testis tissue contains tubules and ovary tissue does not.

Testis tissue contains pain receptors and ovary tissue does not.

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

Explanation

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

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

Estrogen

FSH

LH

Oxytocin

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.

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.