Question 1

Outline the cell theory. [3]

Accepted Answer

All living organisms are made of cells
Cells are the smallest unit of life
All cells come from preexisting cells

Question 2

Outline exceptions to the cell theory. [3]

Accepted Answer

Striated muscle cells
Giant algae
Aseptate Fungal Hyplae

Question 3

Calculate the magnification of drawings. [1]

Accepted Answer

magnification = size of image/actual size of the specimen

Question 4

State all functions of life. [7]

Accepted Answer

Growth, Reproduction, Homeostasis, Excretion, Nutrition, Response to stimuli, Metabolism

Question 5

State the relationship between cell size and surface area:volume ratio. [1]

Accepted Answer

Larger cell, smaller ratio

Question 6

Explain the importance of surface area:volume ratio in respect to heat. [2]

Accepted Answer

When ratio is too small, cells may overheat since there is more heat produced by metabolism than lost.

Question 7

Explain the importance of surface area:volume ratio in respect to resource exchange. [2]

Accepted Answer

If ratio is too small, substances will not enter the cell as quickly as required and waste products will accumulate because of fast production.

Question 8

Outline the key properties of stem cells. [3]

Accepted Answer

Can divide again and again
Useful for growth of new cell tissues or replacement of cells
Not fully differentiated; can differentiate to produce different cell types

Question 9

Outline the usefulness of stem cells. [2]

Accepted Answer

Produce regenerated tissue (burns); healing diseases (type 1 diabetes)

Question 10

Describe two examples for therapeutic uses of stem cells. [4]

Accepted Answer

Stargard's Disease > causes blindness. Stem cells injected in eye.
Leukemia > blood cancer that begins in bone marrow. Stem cells injected in bone marrow.

Question 11

State the possible sources of stem cells. [3]

Accepted Answer

Embryo, Umbilical cord, Adult tissues (bone marrow)

Question 12

Outline the most unethical way to procure stem cells. [2]

Accepted Answer

From embryos. Can possibly kill the embryo.

Question 13

Outline the most ethical way to procure stem cells. [2]

Accepted Answer

From umbilical cord. Does not cause harm, although stem cell amount is limited.

Question 14

State the three stages of binary fission. [3]

Accepted Answer

DNA is replicated
DNA copies move to opposite sides of the cell
Cell divides

Question 15

State two differences between light and electron microscopes. [2]

Accepted Answer

1. Electron microscopes have a higher resolution
2. Light microscopes have less magnification.

Question 16

Outline the structure of a phospholipid. [2]

Accepted Answer

Made of two hydrophobic tails and a hydrophilic head.

Question 17

Describe what happens when the phospholipid bilayer comes in contact with water. [2]

Accepted Answer

Contact with water in hydrophobic region will cause destabilisation. Hydrophilic maintains stability.

Question 18

Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain its stability. [3]

Accepted Answer

The fluid state allows individual phospholipids to move in bilayer. Allows cell to be flexible. Aids with endo/exocytosis

Question 19

State the creators of the current membrane model (fluid mosaic model). [1]

Accepted Answer

Singer and Nicolson

Question 20

Describe the function of cholesterol in membrane fluidity. [3]

Accepted Answer

Interacts with the fatty acid tails of phospholipids to moderate membrane properties; reduces fluidity; separates phospholipid tails.

Question 21

State the position, structure and function of membrane proteins. [6]

Accepted Answer

Peripheral proteins; hydrophilic and not embedded in the membrane, more active = more proteins
Integral proteins; transmembrane proteins with hydrophobic surfaces; acts like pump

Question 22

Distinguish between passive and active transport. [2]

Accepted Answer

Passive transport = movement of particles from high to low concentration
Active transport = movement of particles from low to high concentration

Question 23

Distinguish between facilitated diffusion and simple diffusion. [2]

Accepted Answer

Facilitated diffusion = movement of ions that cannot diffuse in bilayer and pass through proteins instead
Simple diffusion = movement of particles passing between phospholipids of the membrane

Question 24

Define osmosis. [2]

Accepted Answer

The passive movement of water molecules across a partially permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Question 25

Outline endosymbiotic theory and state its evidence. [4]

Accepted Answer

States that mitochondria were once bacteria that were engulfed by the main cell. Mitochondria + chloroplasts have their own DNA, are approx. size of bacteria, and have 70s ribosomes.

Question 26

Outline the sequence of events that occur during the four phases of mitosis regarding the chromosomes. [4]

Accepted Answer

Prophase > chromosomes supercoil
Metaphase > chromatids attach to spindle fibers
Anaphase > chromatids separate
Telophase > chromosomes uncoil

Question 27

Outline how cyclins are involved in the cell cycle. [3]

Accepted Answer

Proteins that control specifics in the cell cycle such as fiber formation. They bind to enzymes that attach phosphate groups to other proteins of the cell. Triggers specific functions depending on cell cycle phase.

Question 28

Outline how the mitotic index is found and its use. [2]

Accepted Answer

number of cells in mitotic phases/all cells x100
Used in predicting response of cancer cells in chemotherapy.

ib bio sl topic 1

Cell Biology (excludes organelles)

Question	Answer
Outline the cell theory. [3]	All living organisms are made of cells Cells are the smallest unit of life All cells come from preexisting cells
Outline exceptions to the cell theory. [3]	Striated muscle cells Giant algae Aseptate Fungal Hyplae
Calculate the magnification of drawings. [1]	magnification = size of image/actual size of the specimen
State all functions of life. [7]	Growth, Reproduction, Homeostasis, Excretion, Nutrition, Response to stimuli, Metabolism
State the relationship between cell size and surface area:volume ratio. [1]	Larger cell, smaller ratio
Explain the importance of surface area:volume ratio in respect to heat. [2]	When ratio is too small, cells may overheat since there is more heat produced by metabolism than lost.
Explain the importance of surface area:volume ratio in respect to resource exchange. [2]	If ratio is too small, substances will not enter the cell as quickly as required and waste products will accumulate because of fast production.
Outline the key properties of stem cells. [3]	Can divide again and again Useful for growth of new cell tissues or replacement of cells Not fully differentiated; can differentiate to produce different cell types
Outline the usefulness of stem cells. [2]	Produce regenerated tissue (burns); healing diseases (type 1 diabetes)
Describe two examples for therapeutic uses of stem cells. [4]	Stargard's Disease > causes blindness. Stem cells injected in eye. Leukemia > blood cancer that begins in bone marrow. Stem cells injected in bone marrow.
State the possible sources of stem cells. [3]	Embryo, Umbilical cord, Adult tissues (bone marrow)
Outline the most unethical way to procure stem cells. [2]	From embryos. Can possibly kill the embryo.
Outline the most ethical way to procure stem cells. [2]	From umbilical cord. Does not cause harm, although stem cell amount is limited.
State the three stages of binary fission. [3]	DNA is replicated DNA copies move to opposite sides of the cell Cell divides
State two differences between light and electron microscopes. [2]	1. Electron microscopes have a higher resolution 2. Light microscopes have less magnification.
Outline the structure of a phospholipid. [2]	Made of two hydrophobic tails and a hydrophilic head.
Describe what happens when the phospholipid bilayer comes in contact with water. [2]	Contact with water in hydrophobic region will cause destabilisation. Hydrophilic maintains stability.
Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain its stability. [3]	The fluid state allows individual phospholipids to move in bilayer. Allows cell to be flexible. Aids with endo/exocytosis
State the creators of the current membrane model (fluid mosaic model). [1]	Singer and Nicolson
Describe the function of cholesterol in membrane fluidity. [3]	Interacts with the fatty acid tails of phospholipids to moderate membrane properties; reduces fluidity; separates phospholipid tails.
State the position, structure and function of membrane proteins. [6]	Peripheral proteins; hydrophilic and not embedded in the membrane, more active = more proteins Integral proteins; transmembrane proteins with hydrophobic surfaces; acts like pump
Distinguish between passive and active transport. [2]	Passive transport = movement of particles from high to low concentration Active transport = movement of particles from low to high concentration
Distinguish between facilitated diffusion and simple diffusion. [2]	Facilitated diffusion = movement of ions that cannot diffuse in bilayer and pass through proteins instead Simple diffusion = movement of particles passing between phospholipids of the membrane
Define osmosis. [2]	The passive movement of water molecules across a partially permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
Outline endosymbiotic theory and state its evidence. [4]	States that mitochondria were once bacteria that were engulfed by the main cell. Mitochondria + chloroplasts have their own DNA, are approx. size of bacteria, and have 70s ribosomes.
Outline the sequence of events that occur during the four phases of mitosis regarding the chromosomes. [4]	Prophase > chromosomes supercoil Metaphase > chromatids attach to spindle fibers Anaphase > chromatids separate Telophase > chromosomes uncoil
Outline how cyclins are involved in the cell cycle. [3]	Proteins that control specifics in the cell cycle such as fiber formation. They bind to enzymes that attach phosphate groups to other proteins of the cell. Triggers specific functions depending on cell cycle phase.
Outline how the mitotic index is found and its use. [2]	number of cells in mitotic phases/all cells x100 Used in predicting response of cancer cells in chemotherapy.

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