#Question id: 11742
#Unit 6. System Physiology – Plant
Mature sieve elements external view, showing sieve plates. The pores in the sieve plates between the sieve tube elements are open channels, what is the relevance of this open pores in the sieve plates?
#Question id: 1522
#Unit 4. Cell Communication and Cell Signaling
Conversion of a proto-oncogene into an oncogene, also called activation, generally involves a gain-of-function mutation. Following statements are regarding to the mechanisms that produce oncogenes from the corresponding proto-oncogenes.
A. A change in a single base pair in a proto-oncogene that results in a hyperactive or constitutively active protein product.
B. A chromosomal translocation that fuses two genes together to produce a hybrid gene encoding a chimeric protein whose activity, unlike that of the parent proteins, is permanently suppress.
C. A chromosomal translocation that brings a growth regulatory gene under the control of alternative enhancers that cause inappropriate expression of the gene.
D. Amplification of a DNA segment including a proto-oncogene so that numerous copies exist, leading to overproduction of the encoded protein.
Which of the following statements are correct?
#Question id: 12706
#Unit 8. Inheritance Biology
#Question id: 1102
#Unit 4. Cell Communication and Cell Signaling
Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of which of the following molecules?
#Question id: 1527
#Unit 4. Cell Communication and Cell Signaling
Following are the six fundamental properties of malignant tumors. Which of these properties are amenable to study in a cell culture model of cancer?
(I) self-sufficiency in growth signals
(II) insensitivity to antigrowth signals
(III) evasion of apoptosis
(IV) limitless replicative potential
(V) sustained angiogenesis
(VI) tissue invasion and metastasis