Answer: alternative D.
Explanation: For the DNA to have the double strand structure, it is necessary to copy the sequence of the existing DNA strand in a complementary sequence of nucleotides, forming hydrogen bonds between them. The mRNA also uses this strategy when reading the DNA strand during the transcription, in order for the translation to begin.
Answer:
C. Coupled reactions establish an electrochemical gradient across a membrane.
Explanation:
- During cellular respiration in mitochondria, and during photosynthesis in chloroplasts, the electron transport chain requires a proton gradient to pump protons across the membrane by active transport.
- Protons flow back across the membrane by facilitated diffusion through ATP synthase, which utilizes them to phosphorylate ADP to ATP.
- This process of ATP synthesis by harnessing the elctrochemicaal gradient geenrated by the diffusion of protons across the biological membrane through ATP synthase is called chemiosmosis.
Totally. Earth's climate systems are driven by the electromagnetic radiation that comes from the Sun. The incoming radiation that comes from the Sun is reflected by the clouds, passes through Earth's surface, or is even absorbed by the planet's atmosphere. The atmosphere warms thanks to the chemical reactions of larger aerosol particles in the atmosphere absorbing this radiation.
