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

Q: Passage: In order to study these characteristics, Mendel needed to control the pollination of the pea plants through artificial fertilization . Pollination occurs when the pollen from the male reproductive part of a flower, called the anthers , is transferred to the female reproductive part of a flower, called the stigma . Pea plants are self-pollinating , which means the pollen from a flower on a single plant transfers to the stigma of the same flower or another flower on the same plant. In order to avoid self-pollination, Mendel removed the anthers from the flowers on a plant. He then carefully transferred pollen from the anthers of another plant and using a small paintbrush, dusted the pollen onto the stigma of the flowers that lacked anthers. This process caused cross-pollination. The Figure below shows the location of the male and female parts of a flower. Cross-pollination occurs when pollen from one flower pollinates a flower on a different plant. In this way, Mendel controlled the characteristics that were passed onto the offspring. The product of cross-pollination is known as a hybrid. The ability to cross-pollinate pea plants allowed Mendel to study the offspring of two parents with different traits, such as a tall stem or a short stem. Answer: pollination

A: The process of transferring pollen from the male reproductive part of a flower known as the anthers to the female reproductive part of the flower known as the stigma is referred to as what?
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Q: Passage: Monarch butterflies gather in large groups as they migrate 2,500 miles south each fall. They return to the north in the spring. This migration is a cycle that repeats every year. Answer: migration

A: What do we call the seasonal movement of animals?
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Q: Passage: Salmon Larva. This newly hatched salmon larva doesn't look very fish-like. The structure hanging from the larva is the yolk sac. Answer: yolk sac

A:
What is the structure which hangs from a newly hatched salmon larva?
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