Each chromosome (replicated or not) contains 2 chromatids.
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As of 2017, microfossils (fossilised microorganisms) within hydrothermal-vent precipitates dated 3.77 to 4.28 Gya in rocks in Quebec may harbour the oldest record of life on Earth, suggesting life started soon after ocean formation 4.4 Gya during the Hadean Eon.
Explanation:
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Answer:
Explanation:Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthropods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings.
Their versatility has enabled arthropods to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80 percent of all described living animal species, some of which, unlike most other animals, are very successful in dry environments. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab.
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Explanation:
Gas exchange
When a plant is carrying out photosynthesis carbon dioxide needs to move from the air into the leaf. It does this by diffusing through small pores called stomata. At the same time oxygen moves out of the leaf through the stomata. This movement of gases in opposite directions is called gas exchange.