<span>Answer: Cellular differentiation is responsible for one daughter cell becoming a sieve tube whereas the other becomes a companion cell. Cell differentiation occurs as different genes are switched on and off.
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Loss of Rb, an important part of the G1-S transition checkpoint, can result in uncontrolled cell cycle progression and cancer. All of the following would mimic loss of Rb except constitutively active Ras GTPase activating protein. Correct answer: letter E.
Constitutively active Ras GTPase activating protein would not mimic loss of Rb, because it would not directly result in uncontrolled cell cycle progression.
<h3>What is Retinoblastoma (RB)?</h3>
Rb is an important tumor suppressor protein that works to inhibit cell cycle progression by preventing the activation of E2F transcription factors. Constitutively active Ras GTPase activating protein would not directly interfere with the Rb-E2F pathway, which is necessary for uncontrolled cell cycle progression and cancer.
Learn more about the cell cycle:
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Answer: A. Chemical signal
Explanation:
Chemical signal is the type of communication which coordinates actions between neighboring cells
.
This ability originated in single cells organisms and was essential for the evolution of multicellular organisms because after a cell receives a message, it is transferred across the plasma membrane and changes are brought about within the cell in response to this message.
Answer:
The Answer is Letter E.
Explanation:
<em>The way membranes of a eukaryotic cell vary is certain proteins are unique to each membrane. </em>
The eukaryotic cells also contain other membrane-bound organelles such as mitochondria and the Golgi apparatus, and in addition, some cells of plants and algae contain chloroplasts. Unlike unicellular archaea and bacteria, eukaryotes may also be multicellular and include organisms consisting of many cell types forming different kinds of tissue.
Answer:
c
Explanation:
A habitat defines the interaction of organisms with the other factors, which can be living or non-living, while niche describes how that specific organism is linked with its physical and biological environment. Habitat is the part of the ecosystem, while niche plays an important role in the formation of an ecosystem.
