exam questions Flashcards
(10 cards)
Some archae have the enzyme adenylate kinase (AK). This enzyme is similar to AK enzymes found in humans. There are 2 types of this enzyme in humans, AK1 and AK3. Table gives info about these 2 enzymes.
AK1:
location in cell - cytoplasm
substrate - ATP
Role of enzyme - transfers phosphate
AK3:
location in cell - mitochondria
substrate - GTP
role of enzyme - transfers phosphate
The tertiary structures of AK1 and AK3 are similar but not identical.
Analyse the info to deduce why there are 2 AK enzymes
(3)
because they are found in different locations
and the substrates are different
so ACTIVE SITE will be different
Some types of Archaea have only one type of AK enzyme.
This enzyme can catalyse both the reactions shown in the table.
The tertiary structure of this enzyme is different from AK1 and AK3.
AK1:
location in cell - cytoplasm
substrate - ATP
Role of enzyme - transfers phosphate
AK3:
location in cell - mitochondria
substrate - GTP
role of enzyme - transfers phosphate
Explain why Archaea have a different type of AK enzyme
(2)
Archae’s enzymes need to be able to bind to 2 different substrates
and archae dont have mitochondria so doesnt need 2 enzymes
Xylem and phloem tissues transport molecules and ions through plants.
Give the meaning of the term tissue
(1)
its a group of cells which perform a similar function
The table gives some information about the structures of xylem and
phloem tissues.
contain seive plates:
-both xylem + phloem
-xylem only
-phloem only
-neither xylem or phloem
cellulose in cell walls:
-both xyelm + phloem
-xylem only
-phloem only
-neither xylem or phloem
have mitochondria:
-both xylem + phloem
-xylem only
-phloem only
-neither xylem or phloem
state which is true for each statement
(3)
seive plates:
phloem only
cellulose in cell walls:
both xylem and phloem
mitochondria:
phloem only
Describe how sugars are transported through the phloem.
(3)
trasported by mass flow/transport
sucrose is actively transported into phloem by carrier protein
sucrose diffuses into sink
Which of the following is the predominant method of transmission of the
influenza virus?
-contaminated surfaces
-contaminated food
-respiratory droplets
-insect vectors
(1)
respiratory droplets
Symptoms of influenza appear some time after a person is infected with the virus.
Explain why there is a time delay between infection and the symptoms appearing.
(3)
because it takes time for enough cells to be damaged by viruses to cause symptoms
time is taken for virus to attach to host cell
time is taken for new viruses to assemble
Explain why antibiotics should not be taken by people with viral infections.
(2)
antibiotics dont work on viruses as they are not living
and it will act as a selctive pressure to increase antibiotic resistance
The diagram shows the evolutionary relationship between three species of
snailfish and a zebrafish.
Tanaka’s snailfish
Yap hadal snailfish
Mariana hadal snailfish
Zebrafish
Common ancestor
Million years ago
200 100 0
Analyse the diagram to describe the evolutionary relationship between these
four species of fish.
(3)
all 4 fish share a common ancestor
yap hadal and mariana are the most closely related
yap hadal and mariana evolved from same species
3 snailfish is more closely related as share more recent common ancestor
The Mariana hadal snailfish and the Yap hadal snailfish were caught in
separate trenches hundreds of kilometres apart.
Explain how these fish evolved to become separate species
(6)
allopatric speciation as geogrpahical barrier due to different trenches
so conditions are different so different selective pressures eg. temperature
mutations occurred so variation. Advantageous alleles so ones with them survived and reproduced
beneficial allele inherited and increase in frequency over time
gene flow reduced between 2 populations so no longer interbreed together due to reproductive isolation
