Biology exam 3
Global average temperature is also rising. Which type of plant (C3, C4 or CAM) is best adapted to high temperatures?
C4 and CAM because they can close their stomata to avoid water loss.
During translation initiation the P-site is first bound by __________.
Methionine-tRNA
What happens if the operator is deleted from an inducible operon?
It will be transcribed at all times
How does the reduction of pyruvate to lactate during fermentation allow glycolysis to continue in the absence of oxygen?
This reaction is coupled to the oxidation of NADH to NAD+.
In crossing a homozygous recessive with a heterozygote, what is the chance of getting an offspring with the homozygous dominant phenotype?
0%
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of the cross BbTt × BBtt will have black fur and long tails?
1/2
In certain plants, tall is dominant to short trait. If a heterozygous plant is crossed with another heterozygous (tall) plant, what is the probability that the offspring will be short?
1/4
An eukaryoric gene contains 3 exons and 2 introns. How many possible combinations of proteins it can make with at least 2 exons expressed in the protein.
3
A possible sequence of DNA nucleotides that would make the template strand for the polypeptide sequence phe-leu-ile-val would be
3' AAA-GAA-TAA-CAA 5'.
All of the following are true about DNA structure except __________.
3' refers to the Nitrogenous base attached to the 3rd C of dexyribose.
What will be minimal length of open reading frame encoding a protein made up of 100 amino acids?
300
Choose the answer that has these events of protein synthesis in the proper sequence. Note that all the steps in translation may NOT be included. 1) A peptide bond forms between the new amino acid and a polypeptide chain. 2) An aminoacyl-tRNA binds to the A site. 3) Empty tRNA leaves the P site, moves to the E site and leaves the ribosome. 4) A small ribosomal subunit binds with mRNA at the recognition site. 5) Peptidyl tRNA translocates to the P site from A site.
4, 2, 1, 3, 5
ATP Hydrolysis yields 7.3 Kcal/mol free energy and it is coupled with many enzyme reactions that would not otherwise happen. Which of the following reaction can be coupled with ATP hydrolysis to become a spontaneous reaction? A reaction with a ΔG value of _______ Kcal/mol.
4.3
Which of the following will be the mRNA transcribed from the DNA? Note only the 5' to 3' strand is shown. 5'-Promoter............ATGCCGGGACTCTTT-3'.
5'-AUGCCGGGACUCUUU-3'
A couple without any cystic fibrosis symptoms have their first child showing symptoms of cystic fibrosis. What is the probability that their next child will be a carrier for cystic fibrosis without showing any symptoms?
50%
Bacteria divides every 20 minutes by binary fission. How many bacteria will be produced from a single bacterium in 3 hours?
512
Which of the following is least true of RUBISCO as it occurs in green plants? A) It is a highly efficient enzyme for CO2 fixation. B) It is an oligomeric protein consisting of two kinds of monomeric polypeptide chains .C) A component of it is synthesized in the cytoplasmic matrix. D) It catalyzes a reaction of O2 with a C5 molecule.
A
In an analysis of the nucleotide composition of a double stranded DNA to see which bases are equivalent in concentration, which of the following would be true?
A + C = G + T only
Which of the following poison dissipate Δ [H+]?
A chemical that would make the inner mitochondrial membrane leaky to ions
What is the relationship between DNA, a gene, and a chromosome?
A chromosome can contain hundreds of genes, which are composed of DNA.
If the gene encoding enzyme involved in the following biochemical pathway of A --> B --> C --> D --> E is interrupted between C and D, the fungus will NOT be able to grow in the minimal medium supplemented with
A, B and C
When mice were fed with radioactive carbon in glucose (C6H12O6) all the 6 CO2 molecules will be released during which of the following process
Acetyl CoA formation and Krebs cycle
Which of the following statement is not true of glycolysis? A) ATP is used to prime the process B) ATP is made in this process. C) Acetyl CoA is an output of glycolysis D) NADH is produced E) Pi from cytoplasm is used to make ATP
Acetyl CoA is an output of glycolysis
When one consumes excess amounts of carbohydrates, they gain weight and store excess energy as fat. Conversion of carbohydrates to fat will involve the intermediate _________.
Acetyl CoA.
Down syndrome is caused by non-disjunction (not separating) of chromosome 21 resulting in trisomy condition. During which stage of meiosis this non-disjunction could occur?
Anaphase 1 and anaphase 11
The homologous chromosomes separate during ____________________ and their sister chromatids separate during _____________ phase of meiosis.
Anaphase I and Anaphase II
Carotenoids are important to many plants because these pigments are able to: A) remove carbon dioxide from the air. B) absorb wavelengths of light that neither chlorophyll a nor b can absorb. C) absorb water so that hydrolysis can be carried out in the chloroplasts. D) capture UV radiation that is harmful to the DNA in the nucleus of plants cells. E) store electrons for use during the "dark" reactions of photosynthesis.
B
In mitochondrial chemiosmosis, translocation of protons takes place from the matrix into the intermembrane space. Which of the following statements describes the direction of translocation of protons in chloroplasts? A) from the intermembrane space to the matrix B) from the stroma into the thylakoid compartment C) from the light reactions to the Calvin cycle D) from the matrix to the stroma E) from the stroma to the chlorophyll
B
When AZT, a dideoxy nucleotide was added to cancer cells, the DNA replication stopped and cancer cells stopped proliferation. During which stage of such inhibition would happen?
B) S phase
Explain what is meant by the statement: C4 plants separate C3 and C4 processes in space and CAM plants separate C3 and C4 processes in time
Both c4 and cam use pep carboxylase to fix CO2 to avoid photorespiration with less effective RuBisCO.
The inducible operon regulates __________________________pathways and repressible operon regulates ______________________ pathways.
Catabolic....Anabolic
The initiation of the S phase and the M phase of the cell cycle depends on _______ and _______ to make _______.
Cdk; cyclin; MPF.
Which of the following will not be able to transform non-pathogenic bacteria to become pathogenic bacteria?
Cell extract from pathogenic bacteria treated with DNase
Which of the following is an exergonic process that directly helps the endergonic process of ATP synthesis in oxidative phosphorylation?
Chemiosmosis
Which of the following is an example of long-term transcriptional control of gene expression?
Chromosomal DNA is methylated and compacted
How does the chromosome number of each daughter cell is reduced to half the original amount during meiosis?
Chromosomes replicate only once before meiosis I but the cell divides twice.
Which of the following is / are important for enforcing the specificity of protein synthesis?
Correct tRNA being attached to the right amino acid Correct codon matching the right anticodon
The light-independent reactions of photosynthesis are those that A) convert glucose into energy. B) convert chlorophylls into light energy. C) convert water into hydrogen and oxygen. D) convert CO2 into reduced molecules (sugars). E) occur only at night.
D
What is common to both photosystems I and II? A) Both involve the splitting of water to donate an electron to the reaction center. B) Both involve the generation of oxygen. C) Both lose an electron to a primary electron acceptor that passes the electron down an electron transport chain leading to the generation of ATP. D) Both contain a reaction center composed of chlorophyll a. E) Both are found in the stroma.
D
Which type of plant can utilize the Calvin cycle? A) C3 plants B) CAM plants C) C4 plants D) C3, C4, and CAM plants
D
Which of the following reactions will have the lowest vMax and lowest Km when appropriate substrate is used at right temperature? A) Enzyme alone B) Enzyme + substrate C) Enzyme + substrate + activator D) Enzyme + substrate + competitive inhibitor E) Enzyme + substrate + non-competitive inhibitor
Enzyme + substrate + non-competitive inhibitor
When we exercise for a long time without rest, the muscle cells become deprived of oxygen. Which of the following is not produced in a muscle cell under such conditions?
Ethanol
Which of the following would slow down or inhibit key enzymes of Krebs cycle and glycolysis?
Excess amount of citrate
A microtubule polymerization inhibitor, Colchicine is added to actively growing cells. Most of the cells would be found with their ______ phase arrested.
M phase
The light energy is used in photosynthesis, specifically to ____________________
Make ATP and NADPH
An example of an exergonic and exothermic reaction is _______________.
Osmosis
Migratory birds store or carry limited amounts of stored energy or food but fly over long distances. Which of the following process is most utilized in such situations to make the most amount of ATP for their flying?
Oxidative phosphorylation
If a RNA virus with protein capsid was allowed to replicate inside a bacterial cell in the presence of radioactive sulfur. The resulting virus was purified and allowed to infect non-radioactive bacteria. Then the cells were centrifuged to separate the virus from bacteria. Which fraction will contain the highest radioactivity?
Protein coat of virus in the supernatant
The energy to make ATP in oxidative phosphorylation comes immediately from ___________.
Proton motive force
Which of the following will be the result if allolactose binds to the repressor?
Repressor is made inactive and transcription and translation occur.
During which stage of the cell cycle the mismatch repair and telomere repair would happen?
S phase G2 phase (also OK)
The composition of a viral DNA was 30% A, 20% G, 25% C and 25% T. Based on this information, we can say that this DNA is from a _______.
Single stranded DNA virus.
Which of the following statements about mitosis is true?
Two genetically identical daughter cells are formed.
Which of the following mutation in the codon will result in a non-sense mutation in protein?
UGC to UGA
When is cyclic electron flow (at Photosystem I) more important for photosynthesis than non-cyclic electron flow?
When there is abundance of NADPH.
The role of a metabolite that controls a repressible operon is to
bind to the repressor protein and activate it.
explain non competitive inhibitors do
bond to somewhere other than active site and lower vmax
What must happen before an eukaryotic cell can divide?
cell growth
explain what competitive inhibitors do
compete with substrate to bond to active site and raise Km
If there are abundant amounts of tryptophan, then the trp operon will be __________.
completely inactive.
Energy is stored in the form of ________ in the food we eat.
covalent bonds
The energy is stored in the form of ________ in the food we eat.
covalent bonds
where does glycolysis occur?
cytoplasm
where does acetyl coa formation take place?
cytoplasm to matrix
label as exergonic or endergonic active transport
endergonic +
label as exergonic or endergonic photosynthesis
endergonic +
label as exergonic or endergonic protein synthesis
endergonic +
Is DNA replication endergonic or exergonic?
exergonic
label as exergonic or endergonic atp hydrolysis
exergonic -
label as exergonic or endergonic chemiosmosis
exergonic -
label as exergonic or endergonic facilitated diffusion
exergonic -
CAM plants can keep stomata closed in daytime, reducing water loss. This is possible because they __________.
fix CO2 into organic acids during the night by PEP carboxylase
Which of the following process is the most primitive and occurs under both aerobic and anaerobic conditions?
glycolysis
When the photophosphorylation is happening during light reactions, the pH of stroma will ______________ compared to the equilibrium state during night time.
increase as the protons are pumped into thylakoid.
what are the inputs and outputs of acetyl coa
inputs : pyruvates, Coa, Nad+ outputs: co2 acetyl coa nadh
what are the inputs and outputs of glycolysis
inputs: Nad+, glucose, Adp and Pi outputs: pyruvate NADH ATP
Compared to eukarotic genes, prokaryotic genes do not contain ______________________.
introns
where does the krebs cycle take place at
mitochondria matrix
When RuBisCO enzyme was modified to reduce the binding of oxygen to minimize photorespiration, the enzyme activity to fix CO2 to carbohydrate was also decreased. A possible explanation to this result is _______________.
modified enzyme lost the binding to both O2 and CO2.
Citrate binds to the regulatory site of the key regulatory enzyme PFK to inhibit Glycolysis whereas the substrates bind to the catalytic site. This effect of citrate is an example of
non competitive inhibition
Why visible light (wavelength of 400 to 700 nm) alone is useful in photosynthesis and not the high energy UV or long wavelength IR spectrum of light?
optimal energy
Overall, respiration is a/an____________________process that is also _______________________
oxidative.....exergonic
What is the sequence of a polypeptide based on the mRNA sequence 5' UUUUCUUAUUGUCUU 3'?
phe-ser-tyr-cys-leu
What is the single most important process that provides food to eat, oxygen to breath, materials to build houses, make cloths, prepare paper, and stores energy for fuel?
photosynthesis
Which organisms are the only primary producers in this planet?
plants
Tissue specific gene expression of some genes occurs because such genes contains tissue specific
promoters
The phases of meiosis that cause the most variation in the four daughter cells are
prophase I and metaphase I.
Which of the following is NOT involved in the elongation of a polypeptide during translation?
Initiation factor
Which of the following is NOT true about prokaryotic operons?
Introns are removed and exons are expressed from each operon.
What is the stage most of the specialized red blood cells are found in?
G0 phase
A scientist found two different sizes of a same protein obtained from plants and animals. This size difference in same type of protein doing identical function could be due to ___________________________
Glycosylation Deletion of amino terminus
A cross between pea plants with red flowers and plants with white flowers resulted in all offspring with pink flowers. This experimental result demonstrates
Incomplete dominance
culture of E. coli bacteria were grown in media containing 15N isotope resulting in both strands of DNA with the heavier 15N. What would be the composition of DNA if those bacteria were transferred and allowed to replicate 20 times in the presence of a lighter 14N isotope?
The proportion of DNA with 15N -14N will be much lower than the DNA with 14N-14N.
Why is it important to reduce the chromosome numbers in half for sexual reproduction of humans?
The sperm and egg cells fertilize and double the chromosome number.
More free energy is released during the Krebs cycle than during glycolysis, but only 2 moles of ATP is produced for each mole of glucose undergoing glycolysis. Most of the remaining free energy that is produced during the Krebs cycle is used to
reduce NAD+ and FAD.
The reaction as shown below, with reference to FAD, is a __________________ process and FAD is a/an ______________(oxidizing or reducing) agent. FAD + X-H2 --> FADH2 + X
reduction.... ...oxidizing
The reaction shown below is a/an ___________________ and it is catalyzed by _______. Phosphoenolpyruvate + ADP --> Pyruate + ATP
substrate level phosphorylation.......kinase
DNA template of 5' to 3 'direction is copied from the other direction starting at the 3' end of the template DNA. This is because _________
the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. DNA polymerase adds nucleotides only at the 3 'end of the new strand.
When a suspension of algae is incubated in a flask in the presence of light and CO2 and then transferred to the dark, the reduction of 3-phosphoglycerate to glyceraldehyde 3-phosphate is blocked. This reaction stops when the algae are placed in the dark because
the reaction requires ATP and NADPH
Suppose a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
the synthesis of ATP
