cell biology

Question 1

name the two types of cells

Answer 1

prokaryotes and eukaryotes

Question 2

what is the difference between a prokaryote and a eukaryote cell?

Answer 2

PROKARYOTIC
- bacteria
- much smaller
- no nucleus

EUKARYOTIC
- plants and animals
- contain a membrane bound- organelles
- nucleus with genetic material

Question 3

what is a prokaryotic cell wall composed of?

Answer 3

peptidoglycan

Question 4

how is genetic information stored in a prokaryotic cell?

Answer 4

found free within the cytoplasm as…
- chromosomal DNA (single loop of circular DNA)
- plasmid DNA

Question 5

what are plasmids?

Answer 5

• small, circular loops of DNA found free in the cytoplasm and separate from the real DNA
• carry genes to provide genetic advancements (e.g, antibiotic resistance)

Question 6

what is order of magnitude?

Answer 6

a power to the base ten used to quantify and compare size

Question 7

list the five components that makes up both plants and animal cells

Answer 7

• nucleus
• cytoplasm
• cell membrane
• ribosomes
• mitochondria

Question 8

list the three components found only in plant cells

Answer 8

• cell wall
• permanent vacuole
• chloroplasts

Question 9

other than storing genetic information, what is the function of the nucleus?

Answer 9

control cellular activities

Question 10

describe the structure of the cytoplasm

Answer 10

fluid containing enzymes, organelles and dissolved ions and nutrients

Question 11

what is the function of the cytoplasm?

Answer 11

• site of cellular reactions
• transport medium

Question 12

what is the function of the cell membrane?

Answer 12

controls entry and exist of materials in and out of the cell

Question 13

what is the function of the mitochondria?

Answer 13

site of later stages of aerobic respiration, in which ATP is produced

Question 14

what is the function of the ribosomes?

Answer 14

join amino acids in a specific order during translation for protein synthetics

Question 15

what is the plant cell wall made of?

Answer 15

cellulose

Question 16

what is the function of the plant cell wall?

Answer 16

• provides strength
• prevents the cell from bursting when water enters through osmosis

Question 17

what does the permanent vacuole contain?

Answer 17

cell sap (solution of salts, sugars, and organic acids)

Question 18

what is the function of the permanent vacuole?

Answer 18

supports the cell, maintaining turgidity

Question 19

what is the function of the chloroplasts?

Answer 19

site of photosynthesis

Question 20

describe how sperm cells in animals are adapted for their function?

Answer 20

HAPLOID NUCLEUS contains genetic information

TAIL enables movement

MITOCHONDRIA provides energy for tail movement

ACROSOME contains enzymes that digest the egg cell wall

Question 21

describe how nerve cells in animals are adapted for their function

Answer 21

LONG AXON allows electrical impulses to be transmitted all over the body from the cns

DENDRITES from the cell body connect to and receive impulses from other nerve cells, muscles, and glands

MYELIN SHEATH insulates the axon and speed up the transmission of impulses along the nerve cell

Question 22

describe how muscle cells are adapted for their function

Answer 22

MITOCHONDRIA provide energy for muscle contraction

MERGED CELLS IN SKELETAL MUSCLE allows muscle fibre contraction in unison

ARRANGEMENT OF PROTEIN FILAMENTS allows them to slide over each other to produce muscle contraction

Question 23

describe how root hair cells in plants are adapted for their function

Answer 23

LARGE SURFACE AREA to absorb nutrients and water from surrounding soil

THIN WALLS do not restrict water absorption

Question 24

describe how xylem cells in plants are adapted for their function

Answer 24

THICKY, WOODY, WALLS strengthen their structure and prevent collapse

NO MARGINS between cells (upper or lower) to provide a continuous route of water to flow

Question 25

describe how phloem cells in plants are adapted for their function

Answer 25

SEIVE PLATES let dissolved amino acids and sugars be transported up and down the stem COMPANION CELLS provide energy needed for active transport of substances

Question 26

what is cell differentiation?

Answer 26

the process by which cells become specialised

Question 27

why is cell differentiation important?

Answer 27

allows production of different tissues and organs that perform various vital functions in the human body

Question 28

at what point in their life cycle do most animal cells differentiate?

Answer 28

early in their life cycle

Question 29

for how long do plants cells retain the ability to differentiate?

Answer 29

throughout their entire life cycle

Question 30

what is the purpose of cell division in mature animals?

Answer 30

repair and replacement of cells

Question 31

what changes does a cell go through as it differentiates?

Answer 31

becomes specialised by obtaining different sub-cellular structures to enable a specific function to be performed by the cell

Question 32

define resolution

Answer 32

the smallest distance between two objects, that can be distinguished by an observer

Question 33

how does a light microscope work?

Answer 33

- passes a beam of light through specimen - light travels through eyepiece lens - this allows specimen to be observed

Question 34

state the advantages of light microscopes

Answer 34

- inexpensive - easy to use - portable - observe both dead and living specimens

Question 35

what is a disadvantage of a light microscope?

Answer 35

limited resolution

Question 36

how does an electron microscope work?

Answer 36

- uses a beam of electrons, focused using magnets - electrons hit a fluorescent screen, which emit visible light - this produces an image

Question 37

names two types of electron microscopes

Answer 37

- transmission electron microscope - scanning electron microscope

Question 38

what are the advantages of using an electron microscope?

Answer 38

- greater resolution - greater magnification

Question 39

why do electron microscopes have a greater magnification and resolution?

Answer 39

they use a beam of electrons which has a shorter wavelength than photons of light

Question 40

how have electron microscopes enables scientists to develop cell understanding?

Answer 40

- small sub-cellular organisms can be observed in detail (eg, mitochondria) - enables scientists to develop more accurate explanations about how cell structure relates to their functions

Question 41

what are the disadvantages of electron microscopes?

Answer 41

- expensive - large, so less portable - require training to use - only dead specimens can be observed

Question 42

how do bacteria multiply?

Answer 42

binary fission (simple cell division)

Question 43

how often do bacteria multiply?

Answer 43

once every 20 minutes … … if enough nutrients are available and the temperature is suitable

Question 44

state two ways in which bacteria can be grown

Answer 44

- nutrient broth solution - colonies on an agar gel plate

Question 45

what nutrients make up a nutrient broth solution?

Answer 45

all nutrients required for bacteria to grow… - including nitrogen for protein synthesis - carbohydrates for energy

Question 46

what are uncontaminated cultures of microorganisms needed for?

Answer 46

investigating disinfectant and antibiotic action

Question 47

describe the preparation of an uncontaminated culture using aseptic technique

Answer 47

- sterilise glass petri dish and agar gel before placing in autoclave - pour agar into the sterile petri dish and allow to set fully - swirl the bacterial suspension, ensuring that it is well mixed - sterilise the inoculating loop by heating it under bunsen burner flame. leave it to cool - dip the inoculation loop into the microorganism solution and make streaks on the surface of the agar plate - replace the lid of the petri dish and secure with tape - allow plate to dry, then label the half of the petri dish containing the media store it upside down. -