Practise IB Biology HL D1.2 with sequence and expression questions covering transcription, translation, mRNA processing, genetic-code tables and mutation consequences.
130 questions in this syllabus scope, with question parts counted together.
117 papers analysed · Tagging incomplete
Reproduction depends on numerous factors both genetic and hormonal.
Outline the process of transcription.
A strand of mRNA consists of the following nucleotides:
AUUCUGGCUA
Which of the following represents the non-transcribed (sense) strand of the DNA?
TAAGACCGAT
ATTCTGGCTA
UAAGACCAU
AUUCUGGCUA
No public sample questions are available for this syllabus point yet.
Organisms often release chemicals when attacked as part of their defence system. Scientists studied lima bean plants (Phaseolus lunatus) infested with either an armyworm, Spodoptera exigua, or a herbivorous mite, Tetranychus urticae. Both organisms feed on lima bean leaves, causing the leaves to release chemicals.
The study was conducted to see which defence chemicals were produced by lima bean leaves when infested by armyworms or herbivorous mites. The scientists identified a mixture of compounds ( C ) released by the plant when attacked. Two of the chemicals in this mixture were identified (C1 and C2).
The scientists hypothesized that the defence chemicals in C act as signals to produce other chemicals ( X, Y and Z ) that are also involved in the defence of the plant.
The graphs show the amounts of chemicals X, Y and Z produced when the plants were infested by either one of the two herbivores or treated with the different chemicals C1 or C2.
The scientists then used the transcribed DNA of each treatment to study the activation of three genes of the plants' defence system. The DNA was separated by gel electrophoresis. The activation was tested one hour after treatment and again after 24 hours.
Gene 3
Deduce, with a reason, which gene is first transcribed when exposed to C2.
Proteins are an important group of chemicals found in all living organisms.
Explain how polypeptides are produced by the process of translation.
Which statement applies to tRNA?
There is at least one type of tRNA that combines with each known amino acid.
One type of tRNA can combine with all of the known amino acids.
tRNA carries out its main role within the nucleus.
tRNA is produced by the process of translation.
This DNA sequence was used to synthesize a polypeptide.
Which are the bases of the tRNA (anticodons)?
TAC TGA
AUG ACU
ATG ACT
Which of the following is a consequence of the degeneracy of the genetic code?
Codons affected by mutagens always code for non-functional proteins.
There are variations in the amino acid sequences for the same protein.
Some base mutations cause no changes in protein structure.
A codon may code for more than one amino acid in response to environmental changes.
The diagram shows mRNA codons.
The mRNA sequence UGGAACGUA codes for what amino acid sequence?
Glycine-Glutamine-Methionine
Methionine-Glutamine-Glycine
Threonine-Valine-Histidine
Tryptophan-Asparagine-Valine
What are polysomes?
Strings of amino acids
Packages of eight histones with DNA
Many ribosomes joined to one mRNA
Complexes of tRNA with amino acids
A DNA sequence before and after a mutation is shown.
Before mutation 3' TAC TCC TGC TTC 5'
After mutation 3' TAC TGC TGC TTC 5'
The table contains mRNA codons and their associated amino acids.
What would be the effect of this mutation on the translated polypeptide?
Thr would replace Arg.
Cys would replace Ser.
There would be an extra Arg.
There would be no change in the amino acid sequence.
What is a feature of transcription in the single-celled organism shown in the electron micrograph?
mRNA splicing
Removal of introns
Codon-anticodon binding
Synthesis of RNA in a to direction
What is a feature of transcription?
Both strands of a DNA molecule act as a template for mRNA.
Nucleoside triphosphates become nucleotides by losing three phosphates.
RNA polymerase binds to the promoter region.
The sense strand acts as a template for mRNA.
Which regions of DNA do not code for proteins but have other important functions?
Promoters, telomeres, DNA coding for tRNA
Promoters, nucleosomes, introns
Introns, nucleosomes, tandem repeats
Exons, tandem repeats, DNA coding for tRNA
What happens to an RNA molecule in eukaryotes after transcription in order to process it into mRNA?
Introns are added.
Exons are removed.
Adenine nucleotides are added at the 3 'end.
Adenine nucleotides are removed from the 5 ' end.
Variations in the types of antibodies are produced by mRNA splicing. What is an advantage of this process?
Reduces the size of mRNA required for the translation of antibodies
Increases the number of different antibodies that can be synthesized
Ensures that one gene codes for one antibody
Speeds up transcription of antibodies
A ribosome with three binding sites, an mRNA molecule and a tRNA molecule are shown.
What would be the effect of blocking the left-hand binding site labelled X ?
The GGG tRNA would not be able to exit the ribosome.
A second tRNA would not be able to bind.
A second tRNA would enter the right-hand binding site.
The ribosome would move to the left.
Explain the synthesis and activation of pepsin and trypsin.
No public sample questions are available for this syllabus point yet.
