B1.1- cell structures

Question 1

Disadvantages of an EM as opposed to an LM?

Answer 1

Complex to set up sample Expensive to buy and operate Large and difficult to move Specimens are dead

Question 3

What is aim?

Answer 3

Actual magnification= image size/magnification

Question 4

Advantages of a LM as opposed to an EM?

Answer 4

Cheap to buy and operate Portable and lightweight Simple to prepare a sample Specimens can be living or dead

Question 7

What are pili?

Answer 7

Pili are tiny hairlike structures that allows the cell to attach to structures and it also allows it to transfer genetic material between bacteria via conjugation

Question 9

What sub cellular structures do both prokaryotes and eukaryotes have?

Answer 9

Cell wall, cell membrane and cytoplasm

Question 10

What extra sub cellular structures do eukaryotes have?

Answer 10

Vacuole,mitochondria,nucleus and chloroplasts

Question 11

What are bacteria?

Answer 11

Bacteria are the smallest organisms that can carry out the seven life processes MRS GREN movement respiration sensitivity growth reproduction excretion and nutrition

Question 12

What are some examples of eukaryotes?

Answer 12

Any animals or plants

Question 13

What is a cytoplasm?

Answer 13

A jellylike substance. The chemical reactions that keep the cell alive happen there

Question 14

What are the common stains?

Answer 14

Methylene blue- this makes it easier to see the nucleus of an animal cell Iodine solution- this makes it easier to see plant nuclei Crystal violet- this stains bacterial cell walls

Question 15

Disadvantages of an LM as opposed to an EM?

Answer 15

Resolution is only 0.2 micrometres Natural colour is seen

Question 18

What are some examples of prokaryotes?

Answer 18

E. coli Streptococcus

Question 19

Advantages of an EM as opposed to an LM?

Answer 19

Higher resolution of 0.1 Nanometres Black and white images are produced so false colour can be added

Question 20

What is a flagella?

Answer 20

A flagella is a tail like structure that allows the cell to move through liquids

Question 21

What is a plasmid?

Answer 21

A plasmid is a circular piece of DNA that is used to store extra genes. These genes are not needed for a bacteria’s day to day survival but are used in times of stress. (Antibiotics are found there)

Question 22

Why stain cells?

Answer 22

many cells are colourless so scientists often stain them to make them easier to see. Some stains cell the whole cell and some only stain certain sub cellular structures

Question 23

What does a nucleus do?

Answer 23

A nucleus controls the activities of the cell. The nucleus also contains genetic material arranged in chromosomes.This determines the cells function and appearance and also contains instructions to make new cells or organisms

Question 29

What is the resolution of a microscope?

Answer 29

A resolution is defined as the smallest distance between two points that can be seen as separate entities

Question 30

What is a light microscope?

Answer 30

A light microscope passes light through an object placed on the slide on the stage, then through two glass lenses an objective lens and an eyepiece lens

Question 31

What is the formula for total magnification?

Answer 31

Total magnification=eyepiece lens magnification*objective lens magnification

Question 32

What is genetic material?

Answer 32

Genetic material floats around in the cytoplasm. There is a long strand called the bacterial chromosome

Question 33

What is an SEM microscope?

Answer 33

A scanning electron microscope produce a three dimensional image of a surface. They send a bean of electrons across the surface of a sample. The reflected electrons are collected to produce an image

Question 35

What are electron microscopes?

Answer 35

Electron microscopes use electrons instead of light to produce an image. They were developed in the 1930’s to allow scientists to see in greater detail. The greater resolution is achieved by high energy electrons as the light source

Question 36

What is a vacuole?

Answer 36

A vacuole is a watery cell sap that keeps the cell rigid and upright

Question 37

What is a TEM microscope?

Answer 37

Transmission electron microscopes produce the most magnified images. They work in a similar way to a light microscope, electrons are passed through a thin slice of the sample the beam is focused to produce an image

Question 39

What is a chloroplast?

Answer 39

These contain green chlorophyll. Chlorophyll transfers energy from the sun to the plant as light which are used in photosynthesis. These are only in the green parts of the plant

Question 42

What is a cell wall?

Answer 42

This surrounds the cell and is made of a tough fibre called cellulose (peptidoglycan in bacteria)

Question 44

What is a slime capsule?

Answer 44

A slime capsule is the layer outside the cell wall. It protects the bacteria from drying out and from poisonous substances. It also allows the bacteria to stick to smooth surfaces

Question 45

What are the main differences between prokaryotic and eukaryotic cells?

Answer 45

Eukaryotic cells have the genetic material in a nucleus Prokaryotic cells do not have mitochondria Eukaryotes are unicellular and prokaryotes and unicellular Eukaryotes are 10-100 micrometres whereas prokaryotes are 1-10

Question 48

What is a mitochondrion?

Answer 48

A mitochondrion is where respiration takes place. Enzymes react oxygen and glucose to make energy to transfer to the organism

Question 54

What is a cell membrane?

Answer 54

A cell membrane is a selective barrier which controls which substances pass in and out of the cell. The cell membrane contains receptor cells

Question 55

What extra sub cellular structures do prokaryotes have?

Answer 55

Genetic material, pili, slime capsule, plasmids and flagella