Microscope & Cells F4

Question 1

Function of the eyepiece lens

Answer 1

to look through

Question 2

Objective lens magnification

Answer 2

total magnification is: eyepiece x objective lens

Question 3

Function of the stage

Answer 3

holds slide and specimen

Question 4

Function of the focusing knob

Answer 4

moves position of lens or stage to focus

Question 5

Function of the light source

Answer 5

provides light to form an image

Question 6

Why do you use the lowest power of objective lens when using a light microscope?

Answer 6

The field of view is wider, allowing to see more of the cells on the slide and making it easier to find the specimen

Question 7

How do electron microscopes work?

Answer 7

They pass beams of electrons through a specimen

Question 8

What does resolution mean?

Answer 8

The ability of a microscope to see in great detail

Question 9

How do you find the true size of a biological specimen?

Answer 9

size observed / magnification

Question 10

How do you find the magnification of an image of a biological specimen?

Answer 10

size observed / actual size

Question 11

How do you find the magnification of an image?

Answer 11

measured length of scale line / given length of scale line

Question 12

How do you prepare a slide of plant cells?

Answer 12

• take a clean slide
• lift small piece of tissue
• add drops of iodine solution
• view slide at low power

Question 13

Why is iodine solution added?

Answer 13

To stain the cells and make them show clearly

Question 14

Why does the piece of tissue need to be thin?

Answer 14

To allow light from the source to pass through the cells

Question 15

How do you prepare a slide of animal cells?

Answer 15

• rub clean cotton bud on inside of cheek
• smear cotton bud on microscope slide
• add drop of methylene blue stain
• lower coverslip
• view on lowest power

Question 16

What is the function of the vacuole?

Answer 16

contains cell sap and helps cell keep its shape

Question 17

What is the function of the cell wall?

Answer 17

provides support to the cell

Question 18

What is the function of the chloroplast?

Answer 18

contains chlorophyll to trap light during photosynthesis

Question 19

What is the function of the nucleus?

Answer 19

control centre of cell containing genetic information of cell

Question 20

What is the function of the chromosomes?

Answer 20

carry genetic material in genes

Question 21

What is the function of the nuclear membrane?

Answer 21

boundary of the nucleus

Question 22

What is the function of the cytoplasm?

Answer 22

where all chemical reactions take place

Question 23

What is the function of the cell membrane?

Answer 23

selectively permeable, controls what enters and leaves the cell

Question 24

What is the function of the mitochondria?

Answer 24

site of cell respiration

Question 25

What are stem cells?

Answer 25

Undifferentiated cells that divide by mitosis to become a specialised cell

Question 26

What are the properties of stem cells?

Answer 26

- can differentiate into any specialised cell types | - continue dividing by mitosis to produce more stem cells

Question 27

Where can you find stem cells?

Answer 27

- embryos - placenta - umbilical cords - bone marrow

Question 28

Why are embryos favoured over adult stem cells?

Answer 28

- easy to grow - easy to extract - able to develop into many different cell types

Question 29

What are the ethical issues in using embryos for stem cells?

Answer 29

- against some peoples religions | - some believe its against the human rights of the embryo

Question 30

What is peer review?

Answer 30

when different scientists work together in teams to share ideas and results

Question 31

Where do stem cells originate in plants?

Answer 31

from meristems at the apical bud of the shoot

Question 32

Describe the procedure of using stem cells for Leukaemia

Answer 32

- chemo destroys cancerous white blood cells - patient is given transplant of bone marrow from healthy matching donor - donor cells multiply to produce healthy blood cells

Question 33

How else can stem cells be used in medicine?

Answer 33

making retina cells - blindness | making brain cells - parkinson's

Question 34

What are the potential risks of using stem cells to cure Leukaemia?

Answer 34

- chemo leaves patient with no immune system - viruses / diseases may be transferred - tumours may develop of unwanted cells

Question 35

What are 3 examples of organ systems in humans?

Answer 35

- digestive - nervous - reproductive

Question 36

What are the functions of the digestive system?

Answer 36

breaks down large insoluble foods molecules into small soluble molecules (stomach)

Question 37

What are the functions of the nervous system?

Answer 37

makes responses and responds to stimuli (brain)

Question 38

What are the functions of the reproductive system?

Answer 38

production of young (uterus)

Question 39

What are the benefits of having organ systems?

Answer 39

- helps transport substances through the body better - helps communication between cells - improves gas exchange

Question 40

What is surface area to volume ratio?

Answer 40

As the size of the organism increases, its surface area to volume ratio decreases

Question 41

What are the adaptions of exchange surfaces?

Answer 41

- large exchange surface area by having a folded surface | - thin exchange surface for short diffusion distance

Question 42

How is the efficiency of exchanged maximised?

Answer 42

- good blood supply do to the capillary networks | - distribute exchanged materials to all cells

Question 43

What is diffusion?

Answer 43

The movement of molecules from a high to low concentration

Question 44

What is the process of diffusion in the lungs?

Answer 44

Blood continues to take in oxygen from alveolar air spaces provided by concentration of oxygen there is greater than in the blood

Question 45

What factors affect the rate of diffusion?

Answer 45

- temperature (high temp. speeds up movement by increasing kinetic energy) - surface area (greater area for molecules to move through)