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IB Biology Exam with correct answers.
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IB Biology Exam with correct answers.
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IB Biology Exam with correct answersHow do you calculate the magnification of a drawing/image? - .......🔷ANSWERS🔶......✔✔
Magnification=Image size(with ruler) / Actual size(according to scale bar)
How do you calculate the actual size of a magnified specimen? - .......🔷ANSWERS🔶......✔✔ Actual
size=Image size(with ruler) / magnification
By which process do potassium ions move through potassium channels in axons?
- .......🔷ANSWERS🔶......✔✔ Facilitated diffusion
-at rest, the Na-K+ pump expels Na+ ions out of cell, while K+ are put within
-when the neuron fires--> the ions swap locations via facilitated diffusion via Na-K+ channels
What is the theory of endosymbiosis? - .......🔷ANSWERS🔶......✔✔ -eukaryotic cells are believed to
have evolved from early prokaryotes that were engulfed by phagocytosis
-the engulfed prokaryotic cell remained undigested
-contributed new functionality to the engulfing cell
-over generations, the engulfed cell lost some of its independent utility and became a supplemental
organelle
What general evidence supports the theory of endosymbiosis? - .......🔷ANSWERS🔶......✔✔ -
membranes have a double membrane bound
-antibiotics(susceptibility)
-division(mode of replication)
-DNA(presence and structural composition)
-ribosomes(size)
How do mitochondria and chloroplasts provide evidence for endosymbiosis?
- .......🔷ANSWERS🔶......✔✔ eukraryotic mitochondria and chloroplasts have their own circular
DNA
,What are the phases of cell cycle? - .......🔷ANSWERS🔶......✔✔ 1. Interphase
2. Mitosis
3. Cytokinesis
What are the phases of interphase? What are their roles? - .......🔷ANSWERS🔶......✔✔ 1. First
growth phase(G1)=growth and normal metabolic roles
2. Synthesis(S)=DNA replication
3. Second growth phase(G2)=growth and preparation for division
What visually occurs during interphase? - .......🔷ANSWERS🔶......✔✔ -DNA is present as
uncondensed chromatin(not visible under microscope)
-DNA is contained with a clearly defined nucleus
-Centrosomes and other organelles have been duplicated
-Cell is enlarged for preparation for division
What are the phases of mitosis? - .......🔷ANSWERS🔶......✔✔ prophase, metaphase, anaphase,
telophase
peter makes apple toast
What happens during prophase? - .......🔷ANSWERS🔶......✔✔ -DNA supercoils and chromosomes
condense(becoming visible under microscope)
-Chromosomes are comprised of genetically identical sister chromatids(joined at centromere)
-paired centrosomes move to opposite poles
-spindle fibers form
-nuclear membrane breaks down
-nucleus dissolves
What happens during metaphase? - .......🔷ANSWERS🔶......✔✔ -spindle fibers from bother
centromeres connect to the centromere of each chromosome
,-microtubule depolymerisation-->spindle fibers shorten in length and contract
-chromosomes align along the center of the cell(metaphase plate)
What happens during anaphase? - .......🔷ANSWERS🔶......✔✔ -genetically identical sister
chromatids separate(caused by contraction of spindle fibers)
-once the chromatids separate, they are considered individual chromosomes
-genetically identical chromosomes move to opposite poles
what happens during telophase? - .......🔷ANSWERS🔶......✔✔ -once the chromosome sets arrive at
the poles, spindle fibers dissolve
-chromosomes decondense(no longer visible under light microscope)
-nuclear membranes reform around each chromosome set
what is cytokinesis? - .......🔷ANSWERS🔶......✔✔ -process of cytoplasmic division
-cell splits into identical daughter cells
-different in plants and animals
how does cytokineses occur in animal cells? - .......🔷ANSWERS🔶......✔✔ -after anaphase--
>microtubules filaments form a concentric ring around the center of the cell
-microfilaments form a cleavage furrow
-when the furrows meet in the center, the cell pinches off and forms two new cells
-centripetal=separation occurs from outside to inside
how does cytokineses occur in plant cells? - .......🔷ANSWERS🔶......✔✔ -after anaphase-->
carbohydrate-rich vesicles form in a row at the center of the cell
-vesicles fuse together
-early cell plate forms at the middle of the cell
-cell plate extends outwards and fuses with the cell wall
-dividing the cell into two distinct daughter cells
-centrifugal=separation occurs from inside to outside
, what is the mitotic index? why is it important? - .......🔷ANSWERS🔶......✔✔ -the ratio of dividing
cells in a cell population
-prognostic tool in predicting the response of cancer cells to chemotherapy
how do you calculate mitotic index? - .......🔷ANSWERS🔶......✔✔ number of cells in mitosis/total
number of cells
calculate the mitotic index based on the following amount of cells in each stage:
prophase=10
metaphase=3
anaphase=2
telophase=5
interphase=30 - .......🔷ANSWERS🔶......✔✔ total=50
number in mitosis=20
20/50=0.4
explain the difference between catabolism and anabolism/their type of rxt
- .......🔷ANSWERS🔶......✔✔ 1. catabolism=breakdown of complex molecules into simpler
molecules-->hydrolysis rxts breakdown macromolecules into monomers
2. anabolism=synthesis of complex molecules from simpler molecules-->condensation rxt forms
macromolecules from monomers
In which processes are macromolecules broken down into monomers? - .......🔷ANSWERS🔶......✔✔
catabolism and hydrolysis
Which molecule in the body is most suitable long-term energy storage in humans? what does it look
like? - .......🔷ANSWERS🔶......✔✔ triglycerides
What are properties of water? - .......🔷ANSWERS🔶......✔✔ -dipolarity allows for polar associations
with other charged molecules(polar or ionic; adhesion)
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