TEST YOUR KNOWLEDGE ON CELL STRUCTURE AND FUNCTION

You can review the cell structure and functions from the past lessons and then proceed to the multiple choice questions to test your skills.

Here is a link to practice on questions related to the cell structure and functions.

OVERVIEW AND MULTIPLE CHOICE QUESTIONS ON CELL RESPIRATION

We have already discussed cell respiration but here is a recap. Cellular respiration is the process by which the chemical energy trapped in food molecules is released and partially captured in the form of ATP. All the different classes of food substances, carbohydrates, fats, and proteins can all be used as fuels in cellular respiration. They have to be converted to glucose before they can be used in the chemical pathway. The three stages of cellular respiration are:

1. Glycolysis: This occurs in the cytosol. In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules.

2. The Krebs cycle: This occurs in the matrix of the mitochondria. This takes place in the presence of oxygen.It generates a pool of chemical energy which includes ATP, NADH, and FADH_2,  from the oxidation of pyruvate, the end product of glycolysis.

3. Oxidative phosphorylation: This occurs in the electron transport chain. The electron transport chain is located on the inner mitochondrial membrane and consists of a series of molecules, mostly proteins. The electron transport chain allows the release of large amount of chemical energy stored in reduced NAD⁺ (NADH) and reduced FAD (FADH₂). This energy is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH₂). 

In the absence of oxygen, fermentation occurs. Fermentation leads to lactic acid production.

• Each molecule of glucose can generate 36-38 molecules of ATP in aerobic respiration.
•  Only 2 ATP molecules are generated in respiration without oxygen (through glycolysis and fermentation).

Click on this link to try the quiz.

MAKING INFERENCES AND CONCLUSIONS FROM SCIENTIFIC EXPERIMENTS

You will be tested on your understanding of scientific experiments and your ability to make inferences and conclusions from various data, graphs, and scenarios. The science passages below can help you practice on some of these questions.

1. Reading Comprehension 1
2. Reading Comprehension 2
3. Reading Comprehension 3
4. Reading Comprehension 4
5. Reading Comprehension 5
6. Reading Comprehension 6
7. Reading Comprehension 7

WHAT ARE CATECHOLAMINES?

The  nervous system consists of the central and the peripheral nervous systems. The central nervous system consist of the brain and spinal cord while the peripheral nervous system is made up of the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is responsible for fight-and-flight responses whilst the parasympathetic is responsible for calming you down. 

Within the sympathetic nervous system, there are two neurotransmitters: 

• Noradrenaline (also referred to as norepinephrine)
• adrenaline (also referred to as epinephrine)

These are known as catecholamines. 

• Noradrenaline is the main neurotransmitter of the sympathetic nerves in the cardiovascular system. It plays a major role in tonic and reflexive changes in cardiovascular tone. The sympathetic noradrenergic system is active even when the individual is at rest.
•  Adrenaline is the main hormone secreted by the adrenal medulla. Adrenaline is a major determinant of responses to metabolic challenges to homeostasis.  

What are some of the fight-and-flight responses?

• Increased alertness
• Pupil dilatation
• Increased heart rate
• Increased respiratory rate
• Decrease intestinal motility
• Decreased bladder contraction
• Vasoconstriction (constriction of blood vessels)
• Increased blood pressure

VIDEO LESSON ON EYE, EARS, AND BRAIN

MULTIPLE CHOICE QUESTIONS ON MATTER

Here is a link to excellent multiple questions on matter (solids, liquids, and gases).

Click on this link to start the test.

MOST VIEWED TOPICS FOR THIS WEEK

THE STRUCTURE OF THE EAR
TYPES OF TISSUES
ELECTROMAGNETISM AND MAGNETS
ECOLOGY - FOOD CHAIN AND WEB
PRACTICE QUESTIONS ON THE ENDOCRINE SYSTEM
CELL STRUCTURE AND FUNCTION
MODES OF HEAT TRANSFER
BASICS OF ELECTRICITY

REVIEW QUESTIONS ON MATTER

1. Which of the following matter has a fixed shape and volume.
       A. liquid
       B. solid
       C. gas

2. Which of the following matter has no fixed shape and volume.
       A. liquid
       B. solid
       C. gas

3.  Which of the following matter has no fixed shape but fixed volume.
       A. liquid
       B. solid
       C. gas

4. What can you say about the particles of a gas.
      A. Closely packed together
      B. Do not move from each other.
      C. Move freely away from each other.

5. The process by which water is changed to ice is referred to as ________
      A. sublimation
      B. condensation
      C. vaporization
      D. freezing

6. When the particles of a gas gain thermal energy, they tend to move _____
     A. slowly
     B. fast
     C. at the speed

7. The process by which water is changed to vapor is referred to as ________
      A. sublimation
      B. condensation
      C. vaporization
      D. freezing

8. The process by which dry ice is changed to gas is referred to as ________
      A. sublimation
      B. condensation
      C. vaporization
      D. freezing

9. What happens when you increase the pressure on a gas in a rigid container.
     A. The molecules hit harder and often on the sides of the container.
     B. The molecules hit gently and often on the sides of the container.
     C. The molecules hit strong but less often on the sides of the container.
     D. The molecules hit gently but often on the sides of the container.

10. According to Boyle's law, as the volume of a gas is decreased, the pressure of the gas
       A. stays the same.
       B. gets higher.
       C. gets lower.
       D. doubles.

11. As the temperature of a gas in a rigid container gets higher, what happens to its pressure?
       A. stays the same.
       B. gets higher.
       C. gets lower.
       D. doubles.
 

ANSWERS TO QUESTIONS ABOVE

1. Which of the following matter has a fixed shape and volume.
       A. liquid
       B. solid
       C. gas

2. Which of the following matter has no fixed shape and volume.
       A. liquid
       B. solid
       C. gas

3.  Which of the following matter has no fixed shape but fixed volume.
       A. liquid
       B. solid
       C. gas

4. What can you say about the particles of a gas.
      A. Closely packed together
      B. Do not move from each other.
      C. Move freely away from each other.

5. The process by which water is changed to ice is referred to as ________
      A. sublimation
      B. condensation
      C. vaporization
      D. freezing

6. When the particles of a gas gain thermal energy, they tend to move _____
     A. slowly
     B. fast
     C. at the speed

7. The process by which water is changed to vapor is referred to as ________
      A. sublimation
      B. condensation
      C. vaporization
      D. freezing

8. The process by which dry ice is changed to gas is referred to as ________
      A. sublimation
      B. condensation
      C. vaporization
      D. freezing

9. What happens when you increase the pressure on a gas in a rigid container.
     A. The molecules hit harder and often on the sides of the container.
     B. The molecules hit gently and often on the sides of the container.
     C. The molecules hit strong but less often on the sides of the container.
     D. The molecules hit gently but often on the sides of the container.

10. According to Boyle's law, as the volume of a gas is decreased, the pressure of the gas
       A. stays the same.
       B. gets higher.
       C. gets lower.
       D. doubles.

11. As the temperature of a gas in a rigid container gets higher, what happens to its pressure?
       A. stays the same.
       B. gets higher.
       C. gets lower.
       D. doubles.

STEM CELLS

Stem cells are cells that have the potential to develop into many different cell types during early developmental stages and growth. When the stem cell divides, it can remain a stem cell or develop into another cell such as muscle, bone, blood cells, etc. Stem cells are important in the repair of tissues.
Three characteristics of stem cells:

•  They are capable of dividing and renewing themselves for long periods.
•  They are unspecialized.
• They can give rise to specialized cell types.

When unspecialized stem cells give rise to specialized cells, the process is called differentiation.

There are two types of stem cells.

• Embryonic stem cells
• Non-embryonic stem cells (somatic or adult stem cells)

Adult stem cells typically generate the cell types of the tissue in which they reside. For example, a blood-forming adult stem cell in the bone marrow normally gives rise to the many types of blood cells. 

Some specialized adult cells can be reprogrammed to become stem cells under certain conditions. These cells are called induced pluripotent stem cells.

Stem cells offer new potentials for treating diseases such as diabetes and heart diseases. Using stem cells to treat diseases is known as cell-based therapy or regenerative or reparative medicine.

Check out this link: Glossary on stem cell information.