What does the sperm need in order to be allowed through the egg's zona?

One community replacing another as a result of changing abiotic and biotic factor are called

Which of the following invertebrates were not found in shallow seas during the Devonian? A. coral B. brachiopods C. crinoids D. none of the above

Which of the following organisms evolved from dinosaurs? A. birds B. crocodiles C. sharks D. snakes

What is germination?

When a snail is touched it retreats into its shell this is an example of?

Are trilobite fossils found in Cambrian rocks?

8. List at least 5 new discoveries about viruses.

The phospholipid molecule has two parts, the polar end and the bipolar end. True or False?

Giraffes use their extremely long necks to reach the lees high up on a case he had trees which other animals can not reach giving them a food source for which they have few competitors what can you conclude about natural selection from this

Which is a reason that many organisms that have existed on earth have left no fossils?