Bio U1 - 1.1

Question 1

State the three parts of the cell theory.

Answer 1

• The cell is a basic unit of life
• All living things are composed by cells
• Cells come from preexisting cells

Question 2

Outline evidence that supports the cell theory.

Answer 2

Observation and experimentation
- Subcellular components have not performed functions of life
- Spontaneous generation has never been observed
- Tissues from animals, plants, eukariots, bacteria, and fungi have all been shown to have cells

Question 3

Compare the use of the word “theory” in daily language and scientific language

Answer 3

• daily language: doubtful, uncertain
• scientific language: it has been proven through numerous observation and experimentation. There currently no doubt. Well-substantiated.

Question 4

Outline the 7 functional characteristics of life

Answer 4

henrrg m
homeostasis
excretion
nutrition
reproduction
response to stimuli
growth
metabolism

Question 5

​Outline the activities occurring in the volume and at the surface of the cell.

Answer 5

Volume means in the citoplasm and in it many metabolic reactions occur. Metabolic reactions always need reactants (oxygen and nutrients) and produce waste (urea and CO2)

Cell surface refers to the entering and leaving of reactants.

Question 6

Calculate the surface area, volume and SA:V ratio of a cube.

Answer 6

• SA: l^2
• V: l^3
• SA:V = l^2:l^3 = 1/l

Question 7

Explain the benefits and limitations of using cubes to model the surface area and volume of a cell

Answer 7

• Benefits: easier to visualize, manipulate, and measure. The relationship of SA and V between cubes and cells is equal.
• Limitations: cubes and cells are not the same and one should be warry of that

Question 8

Describe the relationship between cell size and the SA:V ratio of the cell.

Answer 8

• As the cell increases the ration becomes smaller
• Larger Cells have less surface area relative to the amount of volume

Question 9

Explain why cells are often limited in size by the SA:V ratio.

Answer 9

Larger cells have a larger metabolism, thus there is a greater need for reactants and a greater production of waste. This then becomes unsustainable as the surface area is too small for such a large metabolism.

Question 10

List three adaptations of cells that maximize SA:V ratios

Answer 10

• Long Extensions (neurons)
• Thin, flattened shape (red blood cells)
• Microvilli (small intestine epithelial cells)

Question 11

Define and provide an example of a unicellular organism.

Answer 11

An organism that consists of only one cell
- Bacteria
- Amoeba
- Paramecium

Question 12

Define and provide an example of a multicellular organism.

Answer 12

Organisms that consists of more than one cell
- Frogs
- Humans
- Plants

Question 13

Define “emergent property.”​

Answer 13

• A property that arises only with many individuals

Question 14

Provide an example of emergent properties at different hierarchical levels of life.

Answer 14

• Cardiac cells contract in synchrony and together become cardiac tissue, which can pump blood and through that perform numerous functions of life

Question 15

Describe features of striated muscle fibers that make them a discrepancy from a typical cell.

Answer 15

• Striated muscle fibers have multiple nuclei and are long. A eukaryotic cell with more than one nuclei.

Question 16

Describe features of red blood cells that make them a discrepancy from a typical cell.

Answer 16

• Red blood cells do not have a nuclei

Question 17

Describe features of aseptate fungal hyphae that make them a discrepancy from a typical cell.

Answer 17

• Aseptate hyphae are not made of clearly defined individual cells. They have a continuous cytoplasm along the length of the hyphae.

Question 18

Describe features of giant algae that make them a discrepancy from a typical cell.

Answer 18

• A huge single celled organism with a single celled nucleus

Question 19

Define magnification.

Answer 19

How much larger an object appears compared to its real size

Question 20

Given the magnification of the ocular and objective lenses, calculate the total microscope magnification.

Answer 20

• Multiply the ocular and objective lens

Question 21

Define “field of view.”

Answer 21

• The diameter of the area visible through the microscope

Question 22

Outline how to determine the diameter of a field of view using low power magnification.

Answer 22

• Use a transparent metric ruler and focus on the scale of the ruler

Question 23

Calculate the field of view diameter of a microscope under medium or high power.

Answer 23

• High power = Smaller field of view
• Diameter (LP) x Magnification Objective (LP) / Magnification Objective (HP) = Diameter (HP)

Question 24

Outline how to estimate the size of a sample in the microscope field of view.

Answer 24

• Estimate the fraction of the field of view the object occupies
• Multiply the field of view size by that estimated fraction
• For example: if an object occupies 3/4 of the FOV and the FOV is 5mm, then multiply 3/4 by 5 and you will know the size of the object

Question 25

Define micrograph.

Answer 25

• It is a picture taken through a microscope to show what has been magnified with detail and precision

Question 26

State why the magnification of a drawing or micrograph is not the same as the magnification of the microscope.

Answer 26

• Drawings distort the form and size of a picture, as we cannot draw such small objects with their precise size

Question 27

Use a formula to calculate the magnification of a micrograph or drawing.

Answer 27

Drawing Magnification = Measured size of drawing /
Size of specimen

• Answers should be rounded to one sig fig

Question 28

Define tissue.​

Answer 28

• A group of cells that specialize in the way and perform the same function
• They are only present in multicellular organisms

Question 29

Define differentiation.​

Answer 29

It is the specialization of cells in functions and structures

Question 30

Outline the benefits of cell specialization in a multicellular organism.

Answer 30

They become better, more efficient, and more economic on performing a task, making the being more complex and having multiple metabolisms.

Question 31

Describe the relationship between cell differentiation and gene expression.

Answer 31

Differentiation is due to different genes from a common genome expressing themselves

Question 32

Define totipotent.

Answer 32

Can become an cell (including placenta in placental mammals)
ex: zygotes

Question 33

Define Pluripotent

Answer 33

Can become any cell excluding the placenta
ex: inner cell mass of a blastocyst

Question 34

Define multipotent

Answer 34

Partially differentiated but can still become multiple different cells that are related
ex: umbilical cord stem cells

Question 35

Define zygote

Answer 35

The cell that results from a sperm fertilizing an egg

Question 36

Define embryo

Answer 36

Ear;y stages of develepment after the zygote divides

Question 37

List two key properties of stem cells that have made them on the active areas of research in biology and medicine today.

Answer 37

• They can differentiate into any cell
• They have unlimited division capability

Question 38

Explain why stem cells are most prevalent in the early embryonic development of a multicellular organism.

Answer 38

• Because it is during this period that the stem less are less differentiated or not differentiated at all, thus the prevalence of them in this early developmental stage. As the body develops, those cells will begin to differentiated and perform specific functions in the body.

Question 39

Contrast the characteristics of embryonic, umbilical cord and adult somatic stem cells.

Answer 39

• Embryonic stem cells: pluripotent, inner mass of the blastocyst
• Umbilical Cord stem cells: multipotent, they can only differentiated into blood cells
• Adult somatic stem cells: they are found in the liver, skin, and bone marrow, and they have limited differentiation

Question 40

Describe characteristics of Paramecium that enable it to perform the functions of life.

Answer 40

H - Homeostasis: Material move across cell membrane
E - Excretion: Anal pore for solids and Contractile Vacuole for liquids (CO2)
N - Nutrition: Heterotrophic (eat through the oral groove, englobes other unicellular beings)
R - Reproduction: Asexual and Sexual
R - Response to stimuli: Cilia (allows them to move and interact with environment)
G - Growth: They grow until their SA:V is unsustainable and then they divide
M - Metabolism: Enzymes in cytoplasm

Question 41

Describe characteristics of Chlamydomonas that enable it to perform the functions of life.

Answer 41

H - Homeostasis: Contractile Vacuoles to move water out of the cell membrane to maintain stable water levels
E - Excretion: Difusion to the cell membrane that then excretes to the environment (O2)
N - Nutrition: Autotrophic (Chloroplasts)
R - Reproduction: Asexual reproduction after the cell is big or though sexual reproduction when the nuclei fuse
R - Response to stimuli: Eyespot and Flagella that are sensitive
G - Growth: They absorb minerals from the environment and through photosynthesis
M - Metabolism: Enzymes in Chloroplast and Cytoplasm

Question 42

Outline the cause and symptoms of Stargardt’s disease.

Answer 42

Cause: Recessively inherited gene that causes the photoreceptors in the center of the retina, the macula, eventually making the person go blind.
Symptoms: Central blindness, while peripheral vision remains intact

Question 43

Explain how stem cells are used in the treatment of Stargardt’s disease.

Answer 43

Coaxing stem cells into growing into retinal pigment epithelium (RPE) would help nourish and support other cells in the eye, effectively curing the blindness.

Question 44

Outline the cause of leukemia

Answer 44

Leukemia is a cancer and it is caused by the mutation of cells in the bone marrow and lymphatic system, the body’s blood-forming tissues

Question 45

Explain how stem cells are used in the treatment of leukemia.​

Answer 45

1. Chemotherapy is done to kill the cells with the cancerous gene in the bone marrow
2. A bone marrow (containing adult blood stem cells) transplant occurs
3. If successful, the adult stem cells establish themselves, divide, and then form new healthy blood cells for the patients

Question 46

Discuss the benefits and drawbacks in using embryonic stem cells.

Answer 46

• Benefits: they divide indefinitely and can differentiate into any cell and they will not have genetic mutations that have accumulated with age. The usage of IVF embryos that would have been thrown away is a greater re-purposing.
• Draw-backs: The destruction of a human embryo is ceasing the life of a potential human being and if the division is not controlled, those cells can become tumorous

Question 47

Discuss the benefits and drawbacks in using cord blood stem cells.

Answer 47

• Benefit: as these cells are harvested from the being, they will not be rejected by it later in life, if the need to use them arises. Easy to obtain and store as well.
• Drawback: they are only multipotent, therefore they can only divide into a specific type of cell, and they must be frozen

Question 48

Discuss the benefits and drawbacks in using adult stem cells.

Answer 48

Benefits: will not be rejected from the body, no major ethical concerns are raised with their use. They can be used to regenerate tissue cell and only need the consent of the adult.
Drawbacks: they are only multipotent, therefore cannot differentiate into any cell and they are hard to obtain and not present in all parts of the body.

Question 49

What is iPSC

Answer 49

It is the reprogramming of human somatic cells into an embryonic-like state in which they obtain the ability to differentiate into any body cell, hence they become pluripotent once again.