Why are ostia important to sponges? a) They are the pores through which water, sperm, and food enter the sponge.
b) are large openings in the sponge that allow the waste to exit.
c) They are what the gel is composed of that connects all the different cells of the sponge together.
d) They pull water into the sponge through the beating of their flagella.

I'm so confused! If someone could help, it would mean a lot. Thank you and PLEASE no links!

Aperson is outside exercising. body temperature begins to rise, and the person starts to sweat. their body temperature then returns to normal, and the body stops sweating. a positive b negative c allosteric d homeopathic

Which organelle stores most of a cell’s dna?

Our planet has experienced five major extinctions in the four billion year history of life. the first, 450 million years ago, occurred shortly after the evolution of the first land-based plants and 100 million years after the cambrian explosion. the second extinction occurred 350 million years ago, causing the formation of coal forests. next earth experienced two mass extinctions during the triassic period, between 250 and 200 million years ago. the fifth mass extinction occurred 65 million years ago, ending the reptilian dominance of the earth. according to richard leakey, the sixth mass extinction is happening right now. leakey suggests that we, the human race, are the cause. each year, at our hand, approximately 50,000 species vanish from earth. he believes that man is destroying earth at a rate comparable with the impact of a giant asteroid. leakey's statistics indicate that 50% of earth's species will become extinct within the next 100 years assuming leakey's hypothesis of a sixth mass extinction to be true, how will we expect the model to change? a) a sharp spike in the graph approximately 100 million years from now b) a dip in the graph, followed by a sharp spike about 100 million years from now c) a sharp spike in the graph immediately following the "0" location of the x axis d) a plateau following the "0" mark on the x axis, followed by a gradual rise to a new peak