Cells

Question 1

How is an electron microscope better than a light microscope?

Answer 1

Allow us to see greater detail in the cells e.g. mitochondria and internal detail of the nucleus and chloroplasts

Question 2

What are some disadvantages of electron microscopes?

Answer 2

Are large and very expensive and require specialised rooms in a lab

Question 3

What is the calculation for magnification?

Answer 3

Magnification = size of image ÷ size of real object

Question 4

Convert 1 mm into micrometer

Answer 4

1mm = 1000µm

Question 5

What organelles are in a plant cell only?

Answer 5

Chloroplast, cellulose cell wall and permanent vacuole

Question 6

What is the function of the nucleus?

Answer 6

Contains genetic information in the form of chromosomes

Question 7

What is the function of the nuclear membrane?

Answer 7

Controls what enters and leaves the nucleus.

Question 8

What is the function of the cytoplasm?

Answer 8

Site of chemical reactions

Question 9

What is the function of the cell wall?

Answer 9

Made of cellulose, helps support the plant and make it tough

Question 10

What is the function of chloroplast?

Answer 10

Contains the green pigment chlorophyll, which traps light energy for photosynthesis

Question 11

What is the function of the permanent vacuole?

Answer 11

Contains cell sap and gives the cell support.

Question 12

What is the function of the mitochondria?

Answer 12

Site of cell respiration

Question 13

What features are found in a bacterial cell?

Answer 13

Plasmid, DNA is free in the cytoplasm

Question 14

What is a plasmid?

Answer 14

A ring of DNA found in bacteria

Question 15

Define stem cell

Answer 15

A stem cell is a simple unspecialised cell in animals and plants that has the ability to differentiate to form specialised cells.

Question 16

Where are stem cells found?

Answer 16

Embyos, bone marrow (adult)

Question 17

What is the difference between embryonic stem cells and adult stem cells?

Answer 17

Embryonic can differentiate into a greater range of cell types
Adult stem cells have a limited range of cell types e.g. blood cells

Question 18

Where are stem cells found in plants?

Answer 18

Meristems (at apices) of roots and stems

Question 19

What are the benefits of using plant stem cells?

Answer 19

Retain ability to divide so can be used for cloning techniques which can produce large numbers of genetically identical plants

Question 20

How is stem cell research validated?

Answer 20

Validated using peer review (other scientists repeat and compare results of experiment)

Question 21

What are the benefits of stem cell?

Answer 21

*bone marrow transplants for treating leukaemia (cancer of white blood cells);
*healing burns;
*treating paralysis

Question 22

What are some risks and ethical implications of stem cells?

Answer 22

*pre-treatment using radio- or chemotherapy lowers the immune system (killing healthy cells too);
*transfer of diseases or viruses from other animals;
*formation of tumours due to uncontrollable stem cell division;
*development of unwanted cell types.
*Kills/destroys embryo

Question 23

How can stem cells be used for treatment of leukaemia?

Answer 23

1.Chemotherapy and radiotherapy are used to kill the cancerous white blood cells
2.This stops the patient’s bone marrow producing new blood cells
3.Patient is given a transplant of bone marrow producing new blood cells from a matching healthy donor
4.If successful, the donor stem cells will multiply and produce healthy blood cells

Question 24

Define tissue

Answer 24

A group of cells that work together to carry out a particular function e.g. blood, skin

Question 25

Define organ

Answer 25

A group of tissues types that work together to carry out a particular function e.g. heart contains muscle, nerve and blood tissues

Question 26

Define organ system

Answer 26

A group of organs that work together to carry out a particular function e.g nervous system contains brain, spinal cord, eyes, muscles

Question 27

How do multi-celled organisms form specialised tissues, organs and organs systems?

Answer 27

Multi-celled organisms can differentiate their cells to form specialised tissues, organs and organs systems.

Question 28

How will an increase in temperature effect diffusion?

Answer 28

Increased temperature, increases the kinetic energy of molecules and increases the rate of diffusion

Question 29

How will an increase in surface area affect diffusion?

Answer 29

Increased surface area, increases the rate of diffusion e.g. villi in ileum; alveoli in lungs

Question 30

How does an increase in concentartion gradient affect diffusion?

Answer 30

A steeper concentration gradient, increases the rate of diffusion e.g. the circulation of blood and the movement of gases away from exchange surfaces maintains the steep concentration gradient

Question 31

What three factors affect diffusion?

Answer 31

Temperature, surface area, concentration gradient

Question 32

Define diffusion

Answer 32

The movement of particles from an area of high concentration to an area of lower concentration. This does not require energy (it is a passive process.)

Question 33

Why cant multicelled organisms use diffusion to obtain oxygen?

Answer 33

Diffusion across the body surface is no longer viable as organisms grow bigger (increase in volume) and contain more cells.

Question 34

How do multicelled organisms obtain oxygen and nutrients?

Answer 34

Multi-celled organisms with a small surface area to volume ratio need exchange surfaces (e.g. alveoli, villi, mesophyll cells) and transport systems (circulatory system, respiratory system, vascular system).

Question 35

How do single-celled organisms obtain oxygen and nutrients?

Answer 35

Have a large surface area to volume ratio. They can obtain their oxygen and nutrients from the surrounding environment by diffusion.