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dusya [7]
2 years ago
9

1. When did stromatolites appear on Earth? Archean Hadean Mesozoic Proterozoic

Biology
1 answer:
professor190 [17]2 years ago
7 0

Answer:

Proterozoic

Explanation:

Stromatolites appear on Earth in the end of Proterozoic era because Proterozoic extended from 2500 million years to 542 million years. The stromatolites were present on earth about 542 million years ago. The stromatolites present in large number on the sea shores around the world and are considered as the Earth's first visible life form which can be seen through naked eye. These stromatolites were the first known organisms in which photosynthesis occurs and produce free oxygen..

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Organisms of the same species are equipped with the same survival skills. true or false?
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False , as with deer , a buck has antlers , and a doe has no antlers
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Which of the following is NOT a component of a virus? A. plasma membrane B. protein capsid C. nucleic acid D. tail section
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The answer is A:it does not have a plasma membrane. if you need proof https://www.bing.com/search?q=does%20a%20virus%20have%20a%20plasma%20membrane&qs=n&form=QBRE&sp=-1&p... i did a simple search

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All northern elephant seals come from a very small genetic pool. This is because in the 1890s a large number of them were very q
Mashcka [7]

Answer:

b. the bottleneck effect.

Explanation:

The bottleneck effect occurs when a population's size is reduced for at least one generation. This will result in a very reduced genetic variation, which can lead to further adaptation problems.

The Founder effect has its similarities (in terms of the resulting reduced genetic pool) with the bottleneck effect, BUT it occurs when a new colony is started by a few members of the original population.

The Hardy-Weinberg equilibrium is a principle in population genetics that states that the genetic variation in a population will remain constant from one generation to the next IF certain conditions are present (no migration, aleatory mating, among others), so this is not the answer.

Genetic drift (refers to the change in the frequency of an existing gene variant in a population due to random sampling of organisms, so it is not the answer.

7 0
2 years ago
Match the prokaryotic cell structures to the characteristic of life.
djverab [1.8K]

Answer:

1. Nucleoid: Prokaryotes do not have well defined nucleus. Instead, naked DNA or genetic material is found in the these cells which keeps floating freely in the region of cytoplasm called as mucleoid (nucleus-like). DNA carries the genetic information required for growth, development, metabolic activities and reproduction.

Hence, it must match with b. reproduction: DNA ensures that future generations will be similar to parents

2. Cell wall: Cell wall is the outermost layer surrounding the plasma membrane. It is composed of polysaccharides and is found in bacteria, fungi, and plant cells. In bacteria, it is generally composed of peptidoglycans. Antibiotic such as penicillin acts on the cell wall and creates pores in it which kills the bacteria.

Hence, it can be correctly matched with d. homeostasis: taking an antibiotic, such as penicillin, creates holes in the cell wall of some bacteria, so they lose water and die

3. Flagellum: It is a thread or hair like structure which serves the purpose of locomotion in the cells specially in bacteria, protozoa, spermatozoa etc. In bacteria, it helps in moving in the direction of food and moving away from inhospitable environment.

Hence, it can be correctly matched with e. responding to stimuli: move away from a less hospitable environment or towards a more hospitable environment.

4. Pilus: It is a hair like but rigid structure that protrude from the cell surface of the bacteria. It helps in the process of conjugation by forming a conncetion between cell surface of two bacteria.

Hence, it can be correctly matched with a. reproduction: exchanging genetic material in process of conjugation

5. Ribosomes: Ribosomes serve as the site of protein synthesis in the cell. Bacterial ribosomes are composed of two sub-units with sedimentary constant of 50S and 30S.

Hence, it can be correctly matched with c. maintaining homeostasis: protein is needed for enzymes and repairing structures

6. Cytoplasm: It is gel like material found within the cell (excluding nucleus in case of eukaryotes). All the metabolic activities of the cell generally take place in the cytoplasm of the cell.

Hence, it can be correctly matched with f. homeostasis: using energy, all chemical reactions are performed in the cytoplasm

4 0
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3 years ago
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