A level Biology OCR A Exam Questions AND Correct Answers
Blood pressure graph - ✔✔
Catabolic vs. Anabolic - ✔✔Catabolic - breakdown (lysis)
Anabolic - builds/creates (genesis)
Cell membranes are... - ✔✔Partially permeable barriers
Describe a laser scanning microscope - ✔✔Image displayed on
computer
high resolution
series of optical sections
Microscopes have depth selectivity
Can study whole living organisms
Describe a scanning electron microscope - ✔✔Resolution
10nm, high magnification
Gives 3D image of surface of whole specimen
Electron gun fired and secondary and back-scattered electrons
used to generate image.
,Specimens must be dried and coated (metal film)
Describe a transmission electron microscope - ✔✔resolution
0.1nm, high magnification
Specimen needs to be dehydrated and thinly sliced. It is then
stained with metal salts
Black and white electron micrograph
Describe amylose and amylopectin - ✔✔Make up starch in
plants
Amylopectin has branches but amylose doesn't
Form a spiral with h-bonds
Insoluble in cold water or alcohol
White tasteless powder
Energy store
Describe cellulose - ✔✔Alternate B-glucose molecules upside-
down. Unable to coil or form branches. 1,2 bonds. Cellulose
molecules joined by H-bonds to form microfibrils, then
macrofibrils, then fibres.
Insoluble in water
White powder
,High tensile strength
Makes up cell wall (permeable, strong, flexible)
Describe centrioles - ✔✔Two bundles of microtubules at right
angles to eachother. They are arranged to form a cyclinder.
Forms the spindle before the cell divides
Also involved in formation of cilia and undulipodium
Usually only in animals
Describe chloroplasts - ✔✔-double membrane
-only in plants
-thylakoids containing chlorophyll
-each thylakoid stack called a granum
-Stroma - fluid-filled matrix
-loops of DNA and starch grains
-site of photosynthesis
-Abundant in palisade mesophyll layer
Describe cilia and undulipodia - ✔✔-protrusions surrounded
by cell membrane
-contains microtubules
, -formed from centrioles
-nearly all cells have cilia containing receptors
Describe DNA replication - ✔✔-DNA helicase splits the two
strands by breaking hydrogen bonds
-DNA polymerase adds nucleotide bases from 5' to 3'
-Both strands act as a template
-On lagging strand, built in Okazaki fragments joined by DNA
ligase
-occurs in both directions
Describe glycogen - ✔✔Lots of branches (more than
amylopectin)
Very compact
Granules
Soluble in water
Energy store in liver and muscles
Made up of α glucose.
Branches formed between c-1 and c-6
Describe lysosomes - ✔✔-single membrane
Blood pressure graph - ✔✔
Catabolic vs. Anabolic - ✔✔Catabolic - breakdown (lysis)
Anabolic - builds/creates (genesis)
Cell membranes are... - ✔✔Partially permeable barriers
Describe a laser scanning microscope - ✔✔Image displayed on
computer
high resolution
series of optical sections
Microscopes have depth selectivity
Can study whole living organisms
Describe a scanning electron microscope - ✔✔Resolution
10nm, high magnification
Gives 3D image of surface of whole specimen
Electron gun fired and secondary and back-scattered electrons
used to generate image.
,Specimens must be dried and coated (metal film)
Describe a transmission electron microscope - ✔✔resolution
0.1nm, high magnification
Specimen needs to be dehydrated and thinly sliced. It is then
stained with metal salts
Black and white electron micrograph
Describe amylose and amylopectin - ✔✔Make up starch in
plants
Amylopectin has branches but amylose doesn't
Form a spiral with h-bonds
Insoluble in cold water or alcohol
White tasteless powder
Energy store
Describe cellulose - ✔✔Alternate B-glucose molecules upside-
down. Unable to coil or form branches. 1,2 bonds. Cellulose
molecules joined by H-bonds to form microfibrils, then
macrofibrils, then fibres.
Insoluble in water
White powder
,High tensile strength
Makes up cell wall (permeable, strong, flexible)
Describe centrioles - ✔✔Two bundles of microtubules at right
angles to eachother. They are arranged to form a cyclinder.
Forms the spindle before the cell divides
Also involved in formation of cilia and undulipodium
Usually only in animals
Describe chloroplasts - ✔✔-double membrane
-only in plants
-thylakoids containing chlorophyll
-each thylakoid stack called a granum
-Stroma - fluid-filled matrix
-loops of DNA and starch grains
-site of photosynthesis
-Abundant in palisade mesophyll layer
Describe cilia and undulipodia - ✔✔-protrusions surrounded
by cell membrane
-contains microtubules
, -formed from centrioles
-nearly all cells have cilia containing receptors
Describe DNA replication - ✔✔-DNA helicase splits the two
strands by breaking hydrogen bonds
-DNA polymerase adds nucleotide bases from 5' to 3'
-Both strands act as a template
-On lagging strand, built in Okazaki fragments joined by DNA
ligase
-occurs in both directions
Describe glycogen - ✔✔Lots of branches (more than
amylopectin)
Very compact
Granules
Soluble in water
Energy store in liver and muscles
Made up of α glucose.
Branches formed between c-1 and c-6
Describe lysosomes - ✔✔-single membrane
