Early RNA molecules were able to self replicate, which helps to explain why all organisms share the same genetic code.
Answer:
Cnidarians have groups of similar cells that work together as tissues, while sponges have no tissues, only disconnected regions of specialized cells.
Answer:
Chloroplasts are the ’solar energy plants’ of a cell – they convert light energy into chemical energy
This chemical energy may be either ATP (light dependent) or organic compounds (light independent)
Only photosynthetic tissue possess chloroplasts (e.g. is present in leaves but not roots of plants)
Chloroplasts are thought to have once been independent prokaryotes that were internalised by eukaryotes via endosymbiosis
They have a double membrane structure (due to vesicular coating as part of the endocytotic process)
They have their own DNA (circular and naked) and ribosomes (70S)
Their metabolic processes are susceptible to certain antibiotics
The structure of the chloroplast is adapted to the function it performs:
Thylakoids – flattened discs have a small internal volume to maximise hydrogen gradient upon proton accumulation
Grana – thylakoids are arranged into stacks to increase SA:Vol ratio of the thylakoid membrane
Photosystems – pigments organised into photosystems in thylakoid membrane to maximise light absorption
Stroma – central cavity that contains appropriate enzymes and a suitable pH for the Calvin cycle to occur
Lamellae – connects and separates thylakoid stacks (grana), maximising photosynthetic efficiency
Explanation:
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Plants provide oxygen for the planet and organisms, food/nutrients, and habitats for animals
