IB Biology: Level 1 - Intro to Cells 1.1

Question 1

Cell Theory

Answer 1

1. All living things are composed of cells
2. The cell is the Basic unit of life
3. Cells only come from preexisting cells

Question 2

7 functions of life:

Answer 2

1. Nutrition
2. Metabolism
3. Growth
4. Response to Stimuli
5. Excretion
6. Homeostasis
7. Reproduction

Question 3

Nutrition (as a function of life)

Answer 3

The process by which living things take in materials from its environment for growth and repair

Question 4

Metabolism (as a function of life)

Answer 4

Chemical reactions inside the cell, including cell respiration to release energy

Question 5

Growth (as a function of life)

Answer 5

Cells increase in size over time. When they are large enough and acquire the materials required they may divide

Question 6

Response (as a function of life)

Answer 6

The ability to react to changes in the environment. Receptors in the plasma membrane detect molecules in the environment and send signals to the internal machinery of the cell

Question 7

Excretion (as a function of life)

Answer 7

The process by which living things remove waste products produced by the cell’s activities

Question 8

Homeostasis (as a function of life)

Answer 8

Cells maintain a stable internal environment by carrying out a continuous series of chemical reactions

Question 9

Reproduction (as a function of life)

Answer 9

Producing offspring either sexually or asexually

Question 10

Why is the SA to V ratio of a cell important in the limitation of a cell size?

Answer 10

If a cell grew infinitely large it would reach a point where this balance between SA and V become imbalanced, meaning it used substances more quickly than it could obtain them. At this point cellular activity decrease and/or ceases.

Question 11

What arises from the interaction of component parts of a cell?

Answer 11

Emergent Properties

Question 12

How can it be that all of an organism’s cells have the same genetic information, but the cells have a wide variety of shapes and functions?

Answer 12

All cells are coded, meaning each cell has genes that are expressed, or ‘turned on’ and ‘turned off’. This is because that certain types of cells only require certain genes to create the proteins relevant to that cell.

Question 13

What are key properties of a stem cell?

Answer 13

-undifferentiated (not specialized)
-ability to self-renew
-ability to give rise to various types of cells

Question 14

Two types of stem cells:

Answer 14

Adult and Embryonic

Question 15

Adult Stem Cells

Answer 15

-Found in adult tissue (e.g. neural cells, cardiac muscle, bone marrow)
-Can self-renew many times (but limited)
-Multipotent (only give rise to become cells in the tissue they came from)

Question 16

Embryonic Stem Cells

Answer 16

-Can self renew forever
-Come from the blastocyst stage of an embryo
-Pluripotent (can give rise to become almost anything in body)

Question 17

Totipotent Cells

Answer 17

A potency of a stem cell that allows it to differentiate into absolutely everything include supporting structures of pregnancy

Question 18

Multipotent Cells

Answer 18

A potency of a stem cell that allows it only to differentiate into the cells from their tissue of origin

Question 19

Pluripotent Cells

Answer 19

A potency of a stem cell that allows it to differentiate into almost every cell, excluding supporting structures of pregnancy

Question 20

What factors make striated muscle cells an exception to the cell theory?

Answer 20

-each cell is much larger than most animal cells
-each cell has many nuclei

Question 21

What factors make Giant algae an exception to the cell theory?

Answer 21

-large unicellular organism
-can grow up to 100mm despite having only one nucleus
-An organism of this size would be expected to have more than one cell

Question 22

What factors make Aseptate Fungal Hyphae an exception to the cell theory?

Answer 22

-Does not have cross walls or septa, and so forms an uninterrupted tube-like structure
-Many nuclei spread along tube

Question 23

Difference in nutrition between Paramecium and Chlamydomonas

Answer 23

Ingests small organisms and digests through vesicals VS contains chloroplast and thereby produces own nutrition

Question 24

Difference in Metabolism between Paramecium and Chlamydomonas

Answer 24

Both contain enzymes in the cytoplasm which catalyse the metabolic reactions

Question 25

Difference in Growth between Paramecium and Chlamydomonas

Answer 25

Nutrients from digestion are used for energy and materials needed for growth VS able to grow through the absorption of minerals and photosynthesis

Question 26

Difference in Response between Paramecium and Chlamydomonas

Answer 26

Cilia helps the cell to move, cells moves toward or away from external stimuli VS has an eyespot that allows it to detect the brightest light and therefore it moves towards the light stimuli

Question 27

Difference in Excretion between Paramecium and Chlamydomonas

Answer 27

Waste products in both cells are expelled outside through diffusion

Question 28

Difference in Homeostasis between Paramecium and Chlamydomonas

Answer 28

Both have contractile vacuoles which fill with water and expels it through plasma membrane, maintaining water levels constant

Question 29

Difference in Reproduction between Paramecium and Chlamydomonas

Answer 29

Both reproduce asexually and sexually

Question 30

What is Stargardt’s Disease

Answer 30

A genetic disease that results from a recessive mutation of a gene that effects photo receptor cells in retina

Question 31

How can Stargardt’s disease be treated by stem cells?

Answer 31

Stem cells developed into retina cells which are injected into the eye. These healthy retina cells then attach to retina and remain, increasing quality of vision.

Question 32

Procedure in treating Stargardt’s disease with Stem cells:

Answer 32

1. skin taken from patients arm and used to make stem cells (to avoid rejection)
2. Cocktail of proteins and vitamins are used to coax stem cells into growing healthy retina cells.
3. Healthy retina cells injected into back of patients eye, restoring sight

Question 33

How is Stem cell therapy used to treat Leukemia?

Answer 33

1. Leukemia starts by leukocytes growing and functioning abnormally and are unable to fight infection 2. Chemotherapy used to kill bad leukocytes and allow body to grow healthy ones
2. If chemotherapy is unsuccessful, the bone marrow killed by chemotherapy is replaced with healthy stem cells

Question 34

What are the ethical considerations associated with the therapeutic use of ESCs?

Answer 34

-Technology used could also be used for reproductive cloning
-Creation of stem cell line requires destruction of a human embryo
-embryos are a human life, and thus have the same rights of an individual
-Saving or enhancing the quality of life of an individual doesn’t justify the destruction of the life of another
-ESC research has not produced viable long term treatment whereas adult stem cells have

Question 35

Characteristics of Stem cells obtained from Cord blood stem cells.

Answer 35

-easily obtained and stored
-compatible with tissues of adult that grows from the baby
-Only naturally develop into blood cells
-limited quantities of stem cells in one chord
-the umbilical chord is discarded whether stem cells are taken or not

Question 36

Formula for Magnification:

Answer 36

Magnification = Image size / Actual size

Question 37

Formula for Actual size

Answer 37

Actual size = Image size / Magnification

Question 38

How many Nanometres in a Meter?

Answer 38

10^-9

Question 39

How many Micrometres in a Meter?

Answer 39

10^-6

Question 40

When attempting to draw microscopic structures what conventions should be followed?

Answer 40

1. A title of the specimen included
2. magnification scale included to indicate relative size
3. Identifiable structures should be clearly labelled