Cell Biology Answers

which of the following characteristics of ribozymes provide support to the RNA world hypothesis
Select all that apply
made of RNA
involved in protein synthesis
contain deoxyribose
are polypeptides
are catalysts

Select the phrases that describe the plasma membrane
creates a barrier between the inside and outside of the cell
separates the nucleus and the cytosol
provides a rigid structure that allows the cell to hold its shape
regulates transport of molecules into and out of the cell

Which phrase best describes chromatin
the region that joins chromatids together
single stranded DNA that cannot undergo replication
a fiber composed of DNA and protein molecules
DNA in its duplicated, tightly condensed form

Which of the following events can result in protein misfolding.
a protein adapts a stable but non functional, tertiary structure
contact with a misfolded protein with the same amino acid sequence
a mutation in a gene that inserts an amino acid in a protein
interaction of a partially folded protein with molecular chaperones
the binding of a coenzyme to a protein after normal protein folding

which of the following are true of endosymbiotic theory
explains why mitochondria contain their own genetic information
provides insight about why mitochondria can survive outside of a eukaryotic cell
explains the origin of all organelles found within a eukaryotic cell
states that an ancestral eukaryotic cell engulfed a photosynthetic proteobacteria
explains the origin of some eukaryotic organelles such as chloroplasts

Under which of the following circumstances, will there be a temporary shift from noncyclic to cyclic e– flow during light reaction of photosynthesis?

(1) Absence of PS II
(2) Rise in level of ATP
(3) Rise in level of NADPH + H+
(4) Chl a < Chl b

Which of the following statement is false? and how?

(1) In stroma CO2 is fixed
(2) Chloroplast aligned with their flat surfaces parallel to the lateral walls in low light intensity
(3) With in chloroplast there is a membranous system consisting of grana, stroma lamellae and stroma
(4) The membrane system is responsible for trapping the light energy and also for the synthesis of ATP and NADPH

A cell 'A' having osmotic potential –15 atm and wall pressure 10 atm, present adjacent of cell 'B' having osmotic potential –20 atm and wall pressure 11 atm, the flow of water would be :-

(1) From A to B
(2) From B to A
(3) Equal flow
(4) No flow

Imagine five cells, each of a different shape and all requiring oxygen. Which of the following would have the most satisfactory oxygen supply? Why?
1.A cube 1mm on a side.
2.A cylinder 1mm long and 0.1 mm in diameter.
3.A cylinder 10 mm long and 0.1 mm in diameter.
4.A flat disk 0.1 mm thick and 1 mm in diameter.
5.A sphere 1 mm in diameter.
but explain why or why not each and every one of the above choices is the best choice or not the best choice

How do Vitamin A metabolites harm the membrane?

Thanks!