Question
The first iron ore deposits in rocks appeared about 1.8 billion years ago. What took place to make this occur?
A. Some prokaryotic organisms began to absorb carbon dioxide from seawater.
B. Some eukaryotic organisms began to absorb carbon dioxide from seawater.
C. Some prokaryotic organisms began to release oxygen into seawater.
D. Some eukaryotic organisms began to release oxygen into seawater.
▶️Answer/Explanation
Answer: C. Some prokaryotic organisms began to release oxygen into seawater.
Explanation:
first Photosynthesis process.
- About 1.8 billion years ago, some prokaryotic organisms called cyanobacteria started doing photosynthesis.
- This process released oxygen into the seawater.
- That oxygen reacted with the dissolved iron in oceans, forming iron oxides (rust).
- These oxides settled and became the first iron ore deposits in rocks.
Question
What is evidence for the endosymbiotic theory?
A. RNA can catalyse metabolic reactions.
B. Meteorites contain organic molecules.
C. Amino acids can be synthesized from inorganic compounds.
D. Mitochondria possess their own DNA.
▶️Answer/Explanation
Answer: D. Mitochondria possess their own DNA.
Question
Pasteur used swan-necked flasks and a nutrient broth to demonstrate that spontaneous generation of organisms does not occur on Earth. Some students performed a similar experiment using two swan-necked flasks, one containing broth which had been previously boiled and another containing broth which had not been boiled.
The flasks were left in the school laboratory and observed after one week. What is the evidence against the spontaneous generation theory?
A. Microorganisms died in flask F due to high temperatures.
B. No microorganisms grew in either flask.
C. Microorganisms grew in flask G.
D. No microorganisms grew in flask F but many grew in flask G.
▶️Answer/Explanation
Answer: D.
Explanation:
Pasteur’s experiment showed that Spontaneous generation is the old idea that life can appear from non-living matter.
- Boiling the broth in Flask F killed all existing microorganisms.
- Its swan-neck shape prevented microbes in the air from entering.
- As a result, no new life appeared in Flask F even after a week.
- Flask G was not boiled, so microorganisms already present in the broth or from the air were still alive.
- These microbes grew and multiplied, showing visible signs of life.
This proves that life doesn’t just appear on its own it comes from other life (biogenesis), not from non-living matter.