Questions 15 and 16 i need to know why for 15 4 is correct and for 16 why 1 is correct. !

The answer to 15 is 4 because cellular respiration in the process that produces ATP. Protein synthesis, photosynthesis, and digestion don't directly produce ATP. Carbon dioxide is a by-product of cellular respiration.

Looking at your answer to number 16, I think you might have confused cellular respiration with "regular respiration" or breathing. We breathe in oxygen and breathe out carbon dioxide because the mitochondria in our cells require oxygen to produce ATP, and release carbon dioxide as a byproduct.

Therefore, number 16 isn't cellular respiration. It's not happening within a cell, it's not producing ATP, and mitochondria aren't involved. Instead, it takes place in the lungs (because the alveolus is part of the lungs). You can see that carbon dioxide is being removed from the blood and oxygen is being added. This is the process of gas exchange.

Check out this video for more info on cellular respiration: https://www.khanacademy.org/science/biology/cellular-respiration-and-fermentation/overview-of-cellular-respiration-steps/v/overview-of-cellular-respiration

And this one for more about gas exchange: https://www.khanacademy.org/science/health-and-medicine/respiratory-system/gas-exchange-jv/v/oxygen-movement-from-alveoli-to-capillaries

Hope that helps! Feel free to ask if you need clarification or anything :)

there are mainly three domains in biological classification namely; archaea, bacteria, and eukarya.

archaea includes all the prokaryotic cells which are characterized by their lipid membranes. they have branched hydrocarbon which is attached to glycerol through an ether linkage.

bacteria includes all the prokaryotic cells, the cell membrane of which are made up of the unbranched fatty acid chain. in addition, they are attached to glycerol through an ester bond.

eukarya includes all the eukaryotic cells, that is, the cells contain a nucleus and other membrane-bound cell organelles.

they can be autotrophic as well as heterotrophic, unicellular as well as multicellular

they include kingdoms like protista, plantae, animalia, fungi et cetera.

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