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biology IB exam study guide questions with complete answers.
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biology IB exam study guide questions with complete answers.
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biology IB exam study guide questionswith complete answers
Outline the cell theory exceptions - .......🔷ANSWERS🔶......✔✔ Striated muscle: Extremely long
muscle fibres (up to 300mm long) & multi-nucleated
Giant algae: Extremely long (up to 100mm) but unicellular and one nucleus
Aseptate fungi: Continuos cytoplasm & multi-nucleated
Explain how stem cells are used to treat
Stargardt's and another illness - .......🔷ANSWERS🔶......✔✔ Treated by replacing dead cells in the
retina with functioning ones derived from stem cells
Discuss the advantages and disadvantages
of stem cells - .......🔷ANSWERS🔶......✔✔
Distinguish between prokaryotic and
eukaryotic cells - .......🔷ANSWERS🔶......✔✔ Eukaryotic cells are cells containing membrane-
bound organelles and are the basis for both unicellular and multicellular organisms. In contrast,
prokaryotic cells do not have any membrane-bound organelles and are always part of unicellular
organisms.
Outline the stages of Mitosis - .......🔷ANSWERS🔶......✔✔ Prophase:
DNA supercoils and chromosomes condense (becoming visible under microscope)
Chromosomes are comprised of genetically identical sister chromatids (joined at a centromere)
Paired centrosomes move to the opposite poles of the cell and form microtubule spindle fibres
The nuclear membrane breaks down and the nucleus dissolves
Metaphase:
Microtubule spindle fibres from both centrosomes connect to the centromere of each chromosome
,Microtubule depolymerisation causes spindle fibres to shorten in length and contract
This causes chromosomes to align along the centre of the cell (equatorial plane or metaphase plate)
Anaphase:
Continued contraction of the spindle fibres causes genetically identical sister chromatids to separate
Once the chromatids separate, they are each considered an individual chromosome in their own
right
The genetically identical chromosomes move to the opposite poles of the cell
Telophase:
Once the two chromosome sets arrive at the poles, spindle fibres dissolve
Chromosomes decondense (no longer visible under light microscope)
Nuclear membranes reform around each chromosome set
Cytokinesis occurs concurrently, splitting the cell into two
Outline the Cell cycle phases, describe the
occurrences in each - .......🔷ANSWERS🔶......✔✔ Interphase
The stage in the development of a cell between two successive divisions
This phase of the cell cycle is a continuum of three distinct stages:
G1 - First intermediate gap stage in which the cell grows and prepares for DNA replication
S - Synthesis stage in which DNA is replicated
G2 - Second intermediate gap stage in which the cell finishes growing and prepares for cell division
M phase
The period of the cell cycle in which the cell and contents divide to create two genetically identical
daughter cells
This phase is comprised of two distinct stages:
Mitosis - Nuclear division, whereby DNA (as condensed chromosomes) is separated into two
identical nuclei
, Cytokinesis - Cytoplasmic division, whereby cellular contents are segregated and the cell splits into
two
Outline the process of Transcription - .......🔷ANSWERS🔶......✔✔ 1. RNA polymerase binds to
promoter region on a gene.
2. Section of DNA uncoils into 2 strands with exposed bases. Antisense strand acts as template.
3. Free nucleotides are attracted to their complementary bases.
4. RNA polymerase joins adjacent nucleotides to form phosphodiester bonds.
Explain DNA replication and translation - .......🔷ANSWERS🔶......✔✔ The replication of DNA is
semi-conservative and depends on complementary base pairing
Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds
DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a
template
Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase
Translation is the synthesis of polypeptides on ribosomes
The amino acid sequence of polypeptides is determined by mRNA according to the genetic code
Codons of three bases on mRNA correspond to one amino acid in a polypeptide
Translation depends on complementary base pairing between codons on mRNA and anticodons on
tRNA
Identify cell respiration reactants and
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