D because they are complete systems
Answer:
I think the answer is b. DNA
Answer:
The Earth is 4.6 Billion years old.
QUESTION 2:
Option A is the correct answer.
Hope it helps:)
a. the production of bubbles by the plant when it is in darkness
Explanation:
The indirect observation that will show that the gas produced in this experiment is oxygen is by observing the bubbles on the surface of water in darkness.
Oxygen gas is a by product of photosynthesis. Photosynthesis occurs in the dark and when there is light.
If we observed the bubbles over water, it shows that oxygen gas is given off and the water plant is photosynthesizing. This is a good way to observe the oxygen gas indirectly.
Learn more:
Photosynthesis brainly.com/question/2761166
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A warm fronts move from the south to the north
<u>Explanation</u>:
A warm front are formed when a warm mass of air is pushed into a cold air mass. Since the warm air mass at surface rises above the cold mass of air they often causes stormy weathers. Also due the difficulty of warm air in pushing the cold dense air across the surface of the earth make the warm fronts to move slower when compared to cold fronts. Unstable air produces thunderstorms around the warm fronts. solid red line with red, filled-in semicircles is used to represent a warm front on the map.