Some components of cells are listed.
Cytoplasm
Nucleus
Chloroplasts
Cell Wall
Cell membrane
Which of the components could be observed using a microscope in a prepared slide of leaf epidermal cells, but not in a prepared slide of human cheek cells?
a
Components 3 and 4 only
b
Components 1, 2, and 3 only
c
Components 1 and 5 only
d
Components 2 and 3 only
The correct answer is d) Components 2 and 3 only.
Components 2 and 3, which are the nucleus and chloroplasts, can be observed in a prepared slide of leaf epidermal cells using a microscope. However, these components are not present in human cheek cells, so they cannot be observed in a prepared slide of human cheek cells.
Components 1 (cytoplasm), 4 (cell wall), and 5 (cell membrane) can be observed in both leaf epidermal cells and human cheek cells using a microscope.
Glucose is needed by all cells in order to do cellular respiration. How does glucose, a large molecule, enter cells without using cell energy?
a
using proteins pumps and ATP
b
osmosis moving against the concentration gradient
c
via channel proteins using facilitated diffusion
d
by employing active transport
The correct answer is c) via channel proteins using facilitated diffusion.
Glucose, being a large molecule, requires the help of transporter proteins to enter cells. These transporter proteins are called channel proteins and they facilitate the diffusion of glucose across the cell membrane. This process is known as facilitated diffusion and does not require the cell to use energy (ATP).
Human red blood cells contain 0.9% sodium chloride as a component of their cytoplasm. What would happen if an IV solution containing 1.5% sodium chloride is introduced into a person?
a
The red blood cells will first lose water across their cell membrane, then absorb water across their cell membrane.
b
Their red blood cells would lose water across their cell membrane and begin to shrink.
c
Their red blood cells would absorb water across their cell membrane and begin to swell.
d
The red blood cells would first absorb water across their cell membrane, then lose water across their cell membrane.
The correct answer is b) Their red blood cells would lose water across their cell membrane and begin to shrink.
When the IV solution containing 1.5% sodium chloride is introduced into a person, it creates a hypertonic environment compared to the cytoplasm of the red blood cells, which contains 0.9% sodium chloride. In a hypertonic solution, there is a higher concentration of solute (sodium chloride) outside the cells compared to inside the cells.
As a result, water will move out of the red blood cells (osmosis) to equalize the concentration of solutes on both sides of the cell membrane. This leads to the loss of water from the red blood cells, causing them to shrink or crenate.
Which of the following is NOT an example of homeostasis?
a
During rigorous exercise the heart rate increases to deliver more blood to the cells.
b
When blood glucose is high, the hormone insulin reduces blood glucose.
c
When body temperature rises, nerve impulses cause sweat glands to release more sweat.
d
As humans age, they become more susceptible to disease and cancer.
The correct answer is d) As humans age, they become more susceptible to disease and cancer.
Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes. It involves processes that enable the body to regulate various physiological parameters within a narrow range. Options a), b), and c) all describe examples of homeostasis because they involve specific mechanisms that maintain stability in heart rate, blood glucose levels, and body temperature, respectively.
On the other hand, option d) does not describe an example of homeostasis. Rather, it describes a general trend that occurs as humans age, where their susceptibility to disease and cancer increases. While homeostasis helps regulate various aspects of the body, it does not prevent all diseases or the effects of aging.
If a red blood cell is placed in a HYPOTONIC solution, what will most likely happen to the cell?
a
water moves into the cell causing it to burst.
b
salt moves into the cell causing it to burst.
c
water moves out of the cell causing it to shrink.
d
salt moves out of the cell causing it to shrink
The correct answer is a) water moves into the cell causing it to burst.
When a red blood cell is placed in a hypotonic solution, it means that the solute concentration outside the cell is lower than inside the cell. In this case, water moves into the cell through the process of osmosis to equalize the concentration of solutes on both sides of the cell membrane.
As water moves into the cell, it causes the cell to swell and potentially burst, known as hemolysis. Hypotonic solutions have a higher water concentration compared to the cytoplasm of the red blood cell, resulting in an influx of water and potential bursting of the cell.
Suppose a white blood cell destroys invading bacteria by phagocytosis. Which statement best describes this process?
a
The white blood cells are using active transport, and therefore are using energy.
b
The white blood cells are using passive transport and therefore are not using energy.
c
The white blood cells are using osmosis and therefore are using energy.
d
The white blood cells are using diffusion and therefore are not using energy.
The correct statement is a) The white blood cells are using active transport, and therefore are using energy.
Phagocytosis is an active process in which white blood cells engulf and destroy invading bacteria. It involves the white blood cells extending pseudopods (cellular extensions) to surround the bacteria and form a vesicle known as a phagosome. The phagosome then fuses with lysosomes within the white blood cell, leading to the destruction of the bacteria.
Phagocytosis is an energy-consuming process that requires the white blood cells to actively transport and rearrange their cytoplasmic contents in order to engulf and destroy the bacteria. Therefore, statement a) accurately describes this process as active transport and energy utilization are involved in phagocytosis.
The diffusion of WATER across a selectively permeable membrane is called
a
endo-aqua thermogenesis.
b
facilitated diffusion.
c
active transport.
d
osmosis.
The correct answer is d) osmosis.
Osmosis is the diffusion of water across a selectively permeable membrane, meaning that only water molecules are able to pass through the membrane freely while other solute molecules are restricted. Osmosis occurs in response to a concentration gradient of solutes (such as salts or sugars) on either side of the membrane. Water molecules move from an area of lower solute concentration to an area of higher solute concentration until equilibrium is reached. This movement of water through a semipermeable membrane via diffusion is known as osmosis.
Which of the following statements is NOT part of the "Cell Theory"?
a
Cell is the basic structural and functional unit of life.
b
All cells arise from preexisting cells.
c
All living things or organisms are made of cells.
d
All cells arise spontaneously.
The correct answer is d) All cells arise spontaneously.
The statement "All cells arise spontaneously" is not part of the Cell Theory. The Cell Theory states that:
a) Cell is the basic structural and functional unit of life.
b) All cells arise from preexisting cells.
c) All living things or organisms are made of cells.
The idea that cells arise spontaneously, also known as spontaneous generation, was a widely held belief in early scientific history. However, it was disproven by experiments conducted by Louis Pasteur and others, leading to the acceptance of the principle that cells only arise from preexisting cells. Therefore, statement d) is not part of the Cell Theory.
Viruses are often referred to as non-living infectious particles as they lack many characteristics of living organisms like cellular structure. They do not have the ability to carry out reproduction and metabolism without a host cell.
True or False and why?
a
False - viruses are able to reproduce and use energy without a host cell.
b
True - if a living organism requires a cellular structure, even if they can reproduce - they are by definition non-living.
c
False - viruses, like bacteria, do not have a cellular structure and yet, bacteria are considered living organisms.
d
False - viruses do have a clear cellular structure, including a cell membrane called an envelope.
The correct answer is c) False - viruses, like bacteria, do not have a cellular structure and yet, bacteria are considered living organisms.
Viruses are often considered non-living infectious particles because they lack many characteristics of living organisms. They do not possess cellular structure, such as a cell membrane or organelles, and they cannot carry out reproduction or metabolism without a host cell.
Bacteria, on the other hand, are considered living organisms because they are single-celled organisms that have cellular structures, including a cell membrane, as well as the ability to reproduce and carry out metabolic processes independently.
So, option c) is the correct answer, as it correctly states that viruses lack cellular structure and cannot carry out reproduction or metabolism without a host cell, making them non-living infectious particles.
Viruses are exceptions to the cell theory, but they have some characteristics of living things. What is one of these characteristics?
a
They contain chlorophyll.
b
They are made up of many specialized cells.
c
They contain genetic material.
d
They reproduce by mitosis.
The correct answer is c) They contain genetic material.
Although viruses are considered exceptions to the cell theory because they lack cellular structure and cannot carry out independent reproduction or metabolism, they do have some characteristics of living things. One of these characteristics is that viruses contain genetic material, either in the form of DNA or RNA. This genetic material allows the virus to take over the host cell's machinery and replicate itself. Without the presence of genetic material, viruses would not be able to infect and reproduce within host cells.
A student is learning about infections that can occur in the human body. Infections could be caused by viruses, bacteria, and fungus. The student learns about two infections, influenza and ringworm, and creates a table that describes the infections.
Which of the following statements correctly describes Influenza, an infection caused by a virus?
a
Influenza is caused by a virus because it is a living infectious agent that invades a host cell.
b
Influenza is caused by a virus because it is a non-living infectious agent.
c
Influenza is caused by a fungus, because it is a DNA genome.
d
Influenza is caused by a bacterium because it is a non-living infectious and spreads by spores.
The correct answer is a) Influenza is caused by a virus because it is a living infectious agent that invades a host cell.
Influenza is an infection caused by the influenza virus. The influenza virus is a living infectious agent that invades host cells to reproduce and cause infection. It contains genetic material (DNA or RNA) and uses host cellular machinery to replicate itself. It is classified as a virus, not a fungus or bacterium. Therefore, option a) accurately describes Influenza as being caused by a virus that is a living infectious agent.
Viruses reproduce through the use of host cells. In this process, viruses reproduce by injecting their DNA into the host cell and using the cell's structures to create copies of itself. After numerous copies are made, the host cell bursts and the new viruses are released. Depending on the type of virus and the host cell, hundreds or thousands of viruses can be released in this burst. These viruses then go on to reproduce through new host cells. Bacteria, however, reproduce using binary fission. In this process, a bacterium splits into two identical daughter cells. In favorable conditions, bacteria can divide once every 20 minutes. This means that a single bacterium can turn into a colony of over a billion bacteria in about ten hours.
Which statement correctly compares viral and bacterial reproduction?
a
Both viruses and bacteria must have very large populations in order to reproduce.
b
Both viruses and bacteria can reproduce without the help of other organisms.
c
Both viruses and bacteria can create large populations in a short time period.
d
Both viruses and bacteria must destroy themselves after they have reproduced.
The correct answer is c) Both viruses and bacteria can create large populations in a short time period.
Both viruses and bacteria have the ability to reproduce and create large populations in a relatively short period of time, but the mechanism of reproduction differs between the two.
As mentioned in the passage, viruses reproduce by infecting host cells and using the host cell's structures to create copies of themselves. Once numerous copies are made, the host cell bursts, releasing the new viruses to infect other host cells. This process can lead to the production of hundreds or thousands of viruses in a single burst.
On the other hand, bacteria reproduce through binary fission, where a single bacterium splits into two identical daughter cells. In favorable conditions, bacteria can divide every 20 minutes, leading to exponential growth and the formation of a large bacterial colony in a relatively short period of time.
Therefore, statement c) correctly compares viral and bacterial reproduction, as both can create large populations in a short time period, but they use different mechanisms to do so.
Viruses can progress to two possible scenarios after infecting the host cell. Which of the following is characteristic of the lysogenic cycle?
What is a virus? How do they spread? How do they make us sick?
a
Viral RNA takes over the host cell, making new host cells.
b
Viruses enter the host cell, and rapidly make copies of the host DNA.
c
Viral DNA takes over the host cell, making new viruses that burst out of the cell.
d
Viral DNA is inserted into host DNA, and is replicated when the cell divides.
The correct answer is d) Viral DNA is inserted into host DNA, and is replicated when the cell divides.
In the lysogenic cycle, a characteristic of some viruses, the viral DNA is inserted into the host cell's DNA. This inserted viral DNA is known as a prophage. The host cell then replicates along with its own DNA, copying the viral DNA as well in the process. During subsequent cell divisions, the viral DNA is also passed on to the daughter cells.
In the lysogenic cycle, the viral DNA remains dormant within the host cell's genome and does not immediately produce new viruses. However, under certain conditions, such as exposure to certain triggers or stressors, the viral DNA can become active and initiate the lytic cycle, where the viral DNA is transcribed and translated to produce new viruses that burst out of the host cell.
To briefly address the additional questions:
- A virus is a non-living infectious particle that consists of genetic material (DNA or RNA) enclosed in a protein coat. Viruses cannot reproduce or carry out metabolic processes independently and instead need a host cell to replicate and cause infection.
- Viruses spread from one host to another through various means, such as respiratory droplets, contact with bodily fluids, or vector organisms like mosquitoes that transmit the virus.
- Viruses can make us sick by infecting host cells and disrupting normal cellular functions. This can lead to a range of symptoms and effects, depending on the specific virus and the cells it infects.