Answer:
Active transport: movement against a gradient To move substances against a concentration or electrochemical gradient, a cell must use energy. Active transport mechanisms do just this, expending energy (often in the form of ATP) to maintain the proper concentrations of ions and molecules in living cells.
Answer:the main use of lipids is to store energy
Explanation:If we eat a lot of food, we don't really need all of the energy that we get from it. So, our body stores it away for when we need it later. Hope this helps!
Mitosis results in the formation of two diploid cells while Meiosis results to the formation of four haploid cells. Mitosis is a process that takes place in the somatic cells; a cell that has doubled its genetic material divides to produce two diploid daughter cells while meiosis is a process that take place in the gamete cells where a doubled cell undergoes two rounds of division producing four haploid cells.
The amswer would be B beaucause the excretory system could ger rid of soild and waste
<u>Answer</u>: The correct statements are-
1. At any stage of mitosis a cell has twice as much as DNA in G1.
2. Metabolically active cells can exit, and sometimes re-enter, the cell cycle.
<u>Explanation</u> :
1.. The cell cycle consists of <em>4</em> distinct phases - M phase which is the mitotic phase and the G1, S and G2 phase which together form the interphase. The interphase is preparatory phase wherein the cell grows in size, replicates the DNA etc. whereas the M phase is the one where events related to cell division takes place.
2. The cell has <em>2C</em> amount of DNA during G1 but since the DNA replication takes place during S phase, the amount of DNA <em>doubles up to 4 C</em> and remains so in G2 and M phase until cytokinesis results in the formation of 2 daughter cells.
3. Sometimes, the metabolically active cells can exit the cell cycle and become <em>quiescent</em> until the conditions are favourable. When these quiescent cells recieve the right stimulus they can re enter the cell cycle.
4. Extracellular conditions such as nutrient availability, presence of certain mitogens, growth factors etc. do regulate the cell cycle progression. <em>If any of these extracellular facotrs are limiting the cell cycle is arrested.</em>
5. Once the cell cycle starts, it can be stopped without leading to cell death. When this happens it is known as <em>cell cycle arrest. </em>During this arrest several factors are assessed and if theire is need for repair of DNA then that also takes place. Once, the limitations are overcome or the repair is done, the cell cycle can then continue.
