Topic 1 - Cell Biology

Question 1

What is the difference between prokaryotes and eukaryotes?

Answer 1

Prokaryotes are smaller and simpler cells compared to the complex prokaryotic cells

Question 2

Name the function of these subcellular structures:

1. Nucleus
2. Mitochondria
3. Cytoplasm
4. Cell Membrane
5. Ribosomes
6. Cell Wall
7. Vacuole
8. Chloroplasts

Answer 2

1. Contains genetic material and controls the functions within a cell
2. Provides the energy that the cell needs to work through aerobic respiration
3. Site of most chemical reactions, contains enzymes to control these reactions
4. Holds cell together and controls what goes in and out
5. Where protein synthesis occurs
6. Supports the cell and strengthens it
7. Contains cell sap
8. Contains chlorophyll for photosynthesis

Question 3

How is DNA stored in bacteria cells?

Answer 3

In a long, singular strand of DNA and in small rings of DNA called plasmids

Question 4

What are the advantages of an electron microscope?

Answer 4

They have higher magnification and resolution and allow us to see smaller subcellular structures such as mitochondria which light microscopes do not allow us to do

Question 5

What is the formula for magnification?

Answer 5

Magnification = Image size/Real size

Question 6

How do you prepare a slide for a microscope?

Answer 6

1. Add a drop of water to the middle of a clean slide
2. Place specimen to be examined on the slide
3. Place a drop of iodine on top of the specimen
4. Cover the slip and ensure that there are no air bubbles

Question 7

What role does iodine serve in the slide?

Answer 7

It acts as a stain and highlights subcellular structures

Question 8

Define differentiation

Answer 8

The process through which a cell changes to become specialised to perform a specific function

Question 9

What do you call undifferentiated cells?

Answer 9

Stem cells

Question 10

What are stem cells used for in mature animals?

Answer 10

Repairing and replacing cells that have died or become damaged

Question 11

What adaptations do sperm cells have?

Answer 11

1. Long tail and streamlined head for swimming
2. A lot of mitochondria to provide energy
3. Carries enzymes to dissolve through the egg

Question 12

What adaptations to nerve cells have?

Answer 12

1. Long to cover more distance

2. Have branches to form connections with other cells

Question 13

What adaptations do muscle cells have?

Answer 13

1. They are long so they have space to contact

2. Thye contain lots of mitochondria to provide energy for contraction

Question 14

What adaptations do root hair cells have?

Answer 14

1. They have a large surface area for absorption

2. They are large to cover more ground

Question 15

How could embryonic stem cells be useful for doctors and scientists?

Answer 15

Embryonic stem cells can differentiate into any type of cell and they could be used to cure disease .e.g. make insulin producing cells for people suffering from diabetes

Question 16

Where are stem cells found in adults?

Answer 16

Bone marrow

Question 17

What is the restriction with stem cells from adults?

Answer 17

They can only differentiate into specific types of cell such as blood cells

Question 18

What is therapeutic cloning and why is it useful?

Answer 18

This is where an embryo can be made to have the same genetic material as the person receiving it os the stem cells it produces will not be rejected by a patient

Question 19

Why are some people against stem cells research?

Answer 19

They feel that all embryos have the potential to be a human life and they feel that scientists should focus on finding other sources of stem cells

Question 20

How can stem cells benefit farmers and botanists?

Answer 20

Stem cells found in a plant’s meristem can be used to produce exact copies of that plant to grow more plants cheaply and prevent them from being wiped out

Question 21

How many chromosomes are there in a cell?

Answer 21

46

Question 22

What is mitosis?

Answer 22

The stage in a cell cycle where the cell divides, the cell forms two identical ‘daughter cells’

Question 23

Describe the process of mitosis

Answer 23

1. The chromosomes line up and cell fibres pull them apart and the two arms go to opposite ends of the cell
2. A membrane forms around each set of chromosomes which will become the nuclei of the new cells
3. The cytoplasm and cell membrane divide

Question 24

What is binary fission?

Answer 24

The process through which prokaryotic cells divide

Question 25

Describe binary fission

Answer 25

1. The circular DNA and plasmids replicate 2. The cell expands and the circular strands of DNA move to the pole of the cell 3. The cytoplasm begins to divide and new cell walls begin to form 4. The cytoplasm divides to form two identical daughter cells

Question 26

Define diffusion

Answer 26

The net movement of particles from an area of high concentration to an area of low concentration

Question 27

T/F: the higher the concentration gradient the faster the diffusion

Answer 27

True

Question 28

Name some factors that affect the rate of diffusion

Answer 28

Temperature, concentration gradient, surface area

Question 29

Define osmosis

Answer 29

The net movement of water molecules from an area of high concentration to an area of low concentration through a partially permeable membrane

Question 30

What is a partially permeable mebrane?

Answer 30

A membrane that has very small holes in it, so small that only tiny molecules can pass through it

Question 31

T/F: water molecules only move one way through a partially permeable membrane

Answer 31

False: molecules will move both ways through but because there is a higher concentration on one side there is a higher net movement one way or the other

Question 32

Define active transport

Answer 32

The movement of particles from an area of low concentration to an area of high concentration against the concentration gradient, using energy

Question 33

Give an example of active transport

Answer 33

The movement of water from the soil into root hair cells

Question 34

Give an example of diffusion

Answer 34

Gas exchange in the lungs

Question 35

Give an example of osmosis

Answer 35

The movement of water in and out of a potato or when your feet go wrinkly in the bath

Question 36

What role does active transport play in the human body?

Answer 36

Glucose is taken into the bloodstream from the gut but sometimes there is a higher concentration in the bloodstream meaning that active transport must be used

Question 37

What adaptions do exchange surfaces have?

Answer 37

1. Thin membrane 2. Large surface area 3. Lots of blood vessels 4. Ventilated

Question 38

What do villi do?

Answer 38

Absorb digested food from the small intestine