Modern stromatolites – living fossils. Originating over 3 billion years ago, stromatolites are the oldest known fossils (timeline). Fossilized stromatolites were laid down as colonial structures built by photosynthesizing Cyanobacteria and other microbes.
Answer:
[The recent activities of fossil fuel combustion has had adverse effects on the ozone layer]- B.
Answer:
1: Population; 2: Biome;3: Ecosystem
Explanation:
Population refers to the number of people in a state. Biome is a large area characterised by it's vegetation, soil,climate, and wildlife. Ecosystem is a geographic area where plants, animals and other organisms exists
Answer and Explanation:
The interphase is the previous step before mitosis occurs. The interphase is conformed of the G1, S, and G2 stages.
- During the G1 stage, it occurs a high intense biochemical activity. The cell duplicates its size, and the organelles and other molecules and cytoplasmatic structures duplicate too. Some structures, such as microtubules and actin filaments, are synthesized from zero. The endoplasmic reticulum increases in size and produces a membrane for the Golgi apparatus and vacuoles, lysosomes, and vesicles. During this stage, the pair of centrioles separate, and each centriole duplicates. Mitochondria and chloroplasts also replicate.
The stages S and G2 follow the G1. Once the whole interphase is completed, mitosis occurs.
- During the S stage occurs the DNI replication process. At this point, it also occurs the synthesis of histones and other associated proteins. This is the only stage where the DNI molecule is replicated.
- G2 stage is the final one before the cellular division. Here it begins the slow process of DNI condensation. Duplication of centrioles completes. Structures such as spindle fibers are assembled.
