Mock Flashcards
(17 cards)
Biologists have concluded that the experiment in Figure 1 supports the
cohesion-tension theory of water transport in the xylem.
Explain how this conclusion is supported by the experiment in Figure 1:
1) Water evaporates from the porous pot
2) Creates tension which pull water upwards
3) Cohesion maintains column of water
Describe the importance of each of these properties to living organisms:
1) High heat capacity
2) Large latent heat of vaporisation
1) Buffers changes in temperature
2) provides a cooling effect by evaporation
The solution used to dilute the blood had to have the same water potential as the blood
Explain why:
- Make sure no osmosis
2) So red blood cells don’t burst
A transfusion of blood from a blood group A donor to a blood group B recipient would
cause agglutination of the donated red blood cells.
Use information in Table 1 to explain why.
1) Binding between Antigen A and Antibody Anti-A
2) Causes clumping
Describe how you would use cell fractionation and ultracentrifugation to obtain a sample of mitochondria from muscle tissue.
1) Keep tissue in cold, buffered, isotonic solution
2) Homogenise tissue and filter
3) Centrifuge at low speeds to remove super natant
4) Centrifuge at higher speed to form sediment/ pellet of mitochondria at bottom of tube
Looking at the results of the experiment in Figure 4, the scientists concluded that
splicing had taken place.
Use Figure 4 to describe and explain why the scientists’ conclusion was justified.
1) The loops of DNA have introns
2) The DNA hybrid molecule has exons
3) Introns are removed during splicing
Describe and explain how the results of the experiment in Figure 4 would differ if the scientists had used prokaryotic DNA.
No loops of DNA
No introns in prokaryotic ells
Errors in the precise location of splicing in the DNA molecule can lead to mutations.
Explain why.
Change in base sequence of exons
Orchids form a large family of flowering plants. Scientists analysed genes coding for ribosomal RNA in orchids.
Explain how this analysis allowed the scientists to determine the phylogenetic
relationships between species of orchids.
1) Compares DNA base sequence
2) More similar the DNA sequence the more closely related the species
Name the type of chromosome mutation which would result in the extra chromosome?
Non-disjunction
Chromosomes do not separate
Explain why all the cells of the body have an extra chromosome 18
1) Extra chromosome in gametes
2) Body cells produced by mitosis
Explain how cells with different numbers of chromosomes are produced in mosaic trisomy
Cells with extra chromosome are produced from cell mutation
Explain how VSD can cause higher blood pressure in lungs?
1) More blood moves from left to right ventricle
2) The left ventricle is thicker
3) Greater volume of blood to lungs
Failure to thoroughly wash the well in Step 4 can result in a false positive
Explain why?
1) The 2nd anti body with the enzyme stay
2) The substrate is converted to colour products
A false negative in this test is produced…
Why?
1) Low concentration of antibodies
2) Only primary response
Haemoglobin ( 5 marker)
1) Hb associated with oxygen in the lungs
2) There is high partial pressure of oxygen
3) The binding of a oxygen molecule to Hb makes it easier for another oxygen molecule to bind
4) Oxygen is transported as oxyhaemoglobin in the red blood cells
4) Hb dissociated with oxygen in the tissues
Translation ( 5 marker)
1) The mRNA attaches to ribosomes
2) tRNA anticodons = to mRNA codons
3) tRNA brings species amino acid
4) Forms peptide bonds
5) tRNA is released
4) Ribosome moves along the mRNA
5) Forms a polypeptide
