#Question id: 5561
#Unit 5. Developmental Biology
In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are ________.
#Question id: 5562
#Unit 5. Developmental Biology
In an egg cell treated with a chemical that binds calcium and magnesium ions, the ________.
#Question id: 5563
#Unit 5. Developmental Biology
In mammalian eggs, the receptors for sperm are found in the ________.
#Question id: 5564
#Unit 5. Developmental Biology
At the moment of sperm penetration, human eggs ________.
#Question id: 5565
#Unit 5. Developmental Biology
Among these choices, the largest cell involved in frog reproduction is ________.
#Question id: 5566
#Unit 5. Developmental Biology
In some rare salamander species, all individuals are females. Reproduction relies on those females having access to sperm from males of another species. However, the resulting embryos receive no genetic contribution from the males. Why do you think sperm are necessary for reproduction?