Need help on both questions A and B
st COVID19 closure).docx 3/3 Backgrourd for question 5....
st COVID19 closure).docx 3/3 Backgrourd for question 5. When biologists spot an interesting cellular or physiological or anatomical or developmental trait in a group of organisms that markedly sets them apart from other organisms, they generally seek out one or more adaptive hypotheses that might explain this interesting trait. As a brief and simple example, land vertebrates have internal respiratory gas exchange surfaces (lungs), marine vertebrates have external respiratory surfaces (gills). We hypothesize that external surfaces on fish is needed so the exchange surface is in direct contact with the watery source of necessary O2 to help overcome the slow rate of diffusion in water and we hypothesize that internal exchange surfaces in land animals can work because diffusion rates are faster in air and this internalization is necessary because the internal environment in the lungs can stay moist, a prerequisite for functional gas exchange surfaces. Question 5. A trait in land plants that sets them apart from many other organisms including land animals and including many marine 'plants' (algae) is that the exhibit a sporic alternation of generations. (A) Explain in simplest terms what a sporic alternation of generations is. (B) Propose an adaptive hypothesis as to why land plants have multicellular gametophytes and multicellular sporophytes. Suggestion: As you answer this it may be useful to consider or use in your answer a specific and obvious example like a fern or a lycopodium. TOSHIBA