C. How long does it take a paper bag to break down?
The best answer is (1)
Fossil fuels are commercially available as an energy source.
They are very easy to find. More and more extractions of fossil fuels is going on everyday. With advancement in science and technology, the refineries and extraction procedures have improved a lot. This makes their availability even better.
Fossil fuels are also easily combustible. Most combustion engines need to be powered with little amount of fuel to produce large amount of energy. Very large amounts of electricity can be generated from fossil fuels.
Answer:
Producers give off AND take in carbon dioxide
Explanation:
They give off carbon dioxide from respiration so they return carbon dioxide to the atmosphere. They also use carbon dioxide to synthesize their food.
Answer:
All of these choices are correct.
Explanation:
Cell cycle is the process of growth and division of cell. It comprises of interphase and mitosis. In interphase the cell grows, replicates its genomic content and prepares itself for division. In mitosis the division occurs.
Cell cycle is controlled by a group of kinases called as Cyclin dependent Kinases (CDKs). They act by phosphorylating their substrates. They are of various types like Cdk1, Cdk2, Cdk4 etc. They become active when they bind to a regulatory protein called cyclin. They are also of various types like Cyclin A, Cyclin B, Cyclin C etc. Level of cyclin and corresponding CDK increases and decreases according to the stage of cell cycle. For example in S phase of cell cycle concentration of cyclin A and E shoots up. CDK2 is able to bind to these cyclin molecules and hence it becomes active.
Cell cycle has major checkpoints where the condition of cell is analysed before it proceeds to the next stage of cycle. If any abnormality is detected, repair mechanism is activated or the cell is killed. Checkpoints do not allow cell cycle to proceed in damaged cells.
p53 is a tumor suppressor protein which can halt cell cycle when it detects some abnormality in cell. It usually acts in G1/S checkpoint (before the DNA replication starts in cell) and G2/M checkpoint (before the cell division begins). Hence, all of the above statements are true.
Answer:B. A customer gets sick with E. Coli after eating lettuce that was cut on same cutting board as raw meat.
Explanation:
The glass is not a food and is not considered cross contamination.
The meat was fully cooked and the E. Coli is destroyed.
the same situation as A.
