Mastering biology chapter 6,7,11

question

What is diffusion?
answer

Diffusion is the movement of particles down their concentration gradient.
question

What name is given to the process by which water crosses a selectively permeable membrane?
answer

osmosis. Osmosis is the passive transport of water.
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Describe a cell in hypertonic solution.
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There is a greater concentration of solute outside the cell.
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Describe a cell in hypotonic solution.
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A cell will swell and gain water when placed in a hypotonic solution.
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Describe a plant cell in hypotonic solution.
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In a hypotonic solution plant cells experience a net gain of water and become turgid.
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What happens to a cell in hypertonic solution?
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A cell will lose water when placed in a hypertonic solution.
question

(1) How you would need to modify the outside solution in the left-side drawing to make it hypotonic relative to the solution inside the liposome and (2) How you would need to modify the outside solution in the center drawing to make it hypertonic relative to the solution inside the liposome?
answer

Cell 1 Outside solution hypertonic to inside. Net flow of water out of cell; cell shrinks. Cell 2 – Outside solution hypotonic to inside. Net flow of water into cell; cell swells or even bursts. – (1) Reduce the solute concentration outside the liposome; (2) Increase the solute concentration outside the liposome.
question

The eukaryotic cell overcomes the problem of its larger size by _____.
answer

compartmentalizing cellular functions into various organelles
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Which of the following eukaryotic organelles are found only in algal and plant cells?
answer

chloroplasts
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Mitosis is responsible for what key process in multicellular eukaryotes?
answer

growth, wound repair, reproduction
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During what phase of the cell cycle does the DNA become replicated?
answer

S
question

Which statement is correct concerning the relationship between chromosomes and genes, chromatin, or sister chromatids?
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Each replicated chromosome consists of two sister chromatids. Replication of a chromosome’s single DNA double helix produces two identical DNA copies called sister chromatids.
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Which answer correctly identifies a cell-cycle checkpoint with a criterion for passing it?
answer

G2 checkpoint: Chromosomes have replicated successfully.G2 occurs after S and before M phase, so it is advantageous for the cell to have a checkpoint assessing chromosome replication here.
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Which of these is NOT a carcinogen?: UV light, cigarette smoke, fat, testosterone
answer

All of these substances can cause cancer.
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_____ is a carcinogen that promotes colon cancer.
answer

fat. A diet high in fat increases the risk of both colon and breast cancer.
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What is the consequence of missing or defective Rb proteins for cell-cycle regulation?
answer

E2F is active in the absence of G1 cyclin, resulting in failure of the G1 checkpoint. Normal Rb binds to E2F and keeps it inactive until phosphorylation of Rb by the G1cyclin-Cdk complex releases E2F. If Rb is missing or defective, any E2F that is present will push the cell through the G1 checkpoint regardless of G1 cyclin levels.
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In terms of the relationship between the failure of social controls and cancer, which answer best explains why many cancerous cells have defective forms of the Ras protein?
answer

Ras is part of the signal transduction pathway that triggers G1 cyclin production; many cancer cells have defective forms of Ras that do not become inactivated. Ras is normally activated in response to growth factors and deactivated in their absence. If Ras cannot become deactivated, it constantly sends signals that trigger cell division, contributing to cancer.
question

What two types of defects does a cancerous cell possess?
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Cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive.
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The defining characteristic of a malignant tumor is that _____.
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its cells can spread to other parts of the body
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When cells were first taken from Henrietta Lacks, she was _____.
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suffering from cervical cancer
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How did doctors harvest and culture cells from Henrietta Lacks?
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Cells were taken while she was being treated for cancer many years ago, and these cells have been cultured in the lab ever since.
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Did doctors ask Henrietta Lacks’ permission to take her cells, and was she paid for them?
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She was never told that her cells were being taken, and neither she nor her family has been compensated.
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What property of Henrietta Lacks’ cells was most unusual when they were grown in the laboratory?
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They continue to divide and multiply after decades of culture.
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Cells taken from Henrietta Lacks have been used for experiments leading to _____.
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new treatments for cancer,tests of the effects of atomic radiation on life, the development of a polio vaccine
question

During telophase, the nonkinetochore microtubules _______. disassemble, shorten, or lengthen
answer

disassemble

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