Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: Neutrons consist of fundamental particles known as quarks and gluons. Gluons carry the strong nuclear force that binds together the quarks in a neutron. Answer: gluons
[A]: The two main fundamental particles that make up neutrons are quarks and what else?

[Q]: Passage: They are ectothermic , meaning their temperature depends on the temperature of their environment. Ectothermic animals are cold-blooded in that they cannot raise their body temperature on their own. This is unlike humans, whose temperature is controlled from inside the body. Answer: ectothermic
[A]: What is the term for animals that cannot raise their body temperature on their own?

[Q]: Passage: birth of dizygotic (or fraternal) twins. Because dizygotic twins develop from two eggs fertilized by two sperm, they are no more identical than siblings born at different times. Much less commonly, a zygote can divide into two separate offspring during early development. This results in the birth of monozygotic (or identical) twins. Although the zygote can split as early as the two-cell stage, splitting occurs most commonly during the early blastocyst stage, with roughly 70100 cells present. These two scenarios are distinct from each other, in that the twin embryos that separated at the two-cell stage will have individual placentas, whereas twin embryos that form from separation at the blastocyst stage will share a placenta and a chorionic cavity. Answer: different times
[A]:
Because dizygotic twins develop from two eggs fertilized by two sperm, they are no more identical than siblings born at what?