Practice paper reflection Qs- DIVERSITY

Question 1

Do membranes provide support for the cell

Answer 1

No

Question 2

Changes resulting from gene therapy cannot be passed on to offspring

True or False

Answer 2

False, they can be

Question 3

How many out of
mitosis
meiosis
Apoptosis
are important in determining the body plan of an organism

Answer 3

Mitosis
Apoptosis

(not meiosis)

Question 4

can pathogen transmission through droplets happen in plants

Answer 4

no

Question 5

Explain why typical phenotypic ratio might change due to Autosomal linkage

Answer 5

-Both genes occour on same chromatid
-No independant assortment
-so alleles inherited together / end up in same gamete
-(unless) crossing over occours / chiasma forms between gene loci

Question 6

Y allele codes for a functioning enzyme
y allele codes for an inactve form of this enzyme

Explain why the y allele is recessive

Answer 6

(active) enzyme will still be synthesised even if you only have one Y allele

Question 7

What does a slight change in homeobox genes tell us about the classification of two Animals

Answer 7

-Very little as homeobox genes are highly conserved within kingdoms

-Only tell us that they belong to same kingdom

Question 8

Why don’t you grow bacteria in schools at 35°C

Answer 8

Could encourage growth of human pathogens

Question 9

How do repeats improve an investigation

Answer 9

-reduce impact of anomolous results
-measure /ensure repeatability
-allow calculation of standard deviation/ named stats test
- mean more likely to be accurate /closer to true value

Question 10

Explain why genetic bottleneck can lead to low genetic diversity (2mrk)

Answer 10

-alleles lost
-modern pop descended from few survivers

Question 11

Explain why genetic drift is likely to be of particular concern in the population of 100 cheetahs in Iran

Answer 11

-one Indiv has proportionally higher effect on small population

-(more likely) alleles will be lost from pop.

-(pop.) more likely to become extinct due to Environmental change

Question 12

How to work out nunber of possible variations of genetically different gamete if independant assortment is the only source of genetic variation

Answer 12

2^n.

Where n is the number of haploid chromosomes

Question 13

why is accurate classification of organisms important

when classifying subspecies

Answer 13

-Ensures subspecies do not go extinct
-allows clear communication between scientists
-allow scientists to better understand evolutionary relationships

Question 14

First DNA is extracted from sample tissue

Outline subsequent steps of producing DNA profile

Answer 14

-amplify DNA with PCR
-cut/digest with restriction enzyme
-separate using gel electrophoresis
transfer to paper/nylon
-add fluorescent probe
-use UV light to view

Question 15

outline process of primary succession.
state general principles

Answer 15

Pioneer community
* begins with bare rock
* arrival as seeds or spores
* pioneer species have certain adaptations,
e.g. nitrogen-fixation

Intermediate community
* herb species, including grasses
* followed by shrubs and trees
Climax community
* dominance by a few tree species
* little change over time

General principles
* seral stages
* community and decomposition changes
composition of soil
* increased organic, nitrate or water content

Question 16

explain effect of stabilising selection of beak size in finch

Answer 16

Genetic variation
* pre-existing
* sexual reproduction
* meiosis
* mutation
Differential survival
* overproduction of offspring
* finches with extreme beak depth less
likely to survive
* reason for birds with very small or large
beaks not surviving
Inheritance
* survivors possess alleles for average
beak depth
* alleles for average beak depth more likely
to be inherited by offspring
* increase frequency of these alleles from
one generation to the next