Problem: Memory:

Physical exercise, particularly continuous aerobic exercises such as running, cycling and swimming, has many cognitive benefits and effects on the brain. Influences on the brain include increases in neurotransmitter levels, improved oxygen and nutrient delivery, and increased neurogenesis in the hippocampus. The effects of exercise on memory have important implications for improving children's academic performance, maintaining mental abilities in old age, and the prevention and potential cure of neurological diseases.

What causes decreased oxygen and nutrient delivery?
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A: unanswerable

Problem: Around the 6th century, Slavs appeared on Byzantine borders in great numbers.[page needed] The Byzantine records note that grass would not regrow in places where the Slavs had marched through, so great were their numbers. After a military movement even the Peloponnese and Asia Minor were reported to have Slavic settlements. This southern movement has traditionally been seen as an invasive expansion. By the end of the 6th century, Slavs had settled the Eastern Alps regions.
The Slavs appeared on whose borders around the 6th century?
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Answer: Byzantine borders

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Bacteria often attach to surfaces and form dense aggregations called biofilms or bacterial mats. These films can range from a few micrometers in thickness to up to half a meter in depth, and may contain multiple species of bacteria, protists and archaea. Bacteria living in biofilms display a complex arrangement of cells and extracellular components, forming secondary structures, such as microcolonies, through which there are networks of channels to enable better diffusion of nutrients. In natural environments, such as soil or the surfaces of plants, the majority of bacteria are bound to surfaces in biofilms. Biofilms are also important in medicine, as these structures are often present during chronic bacterial infections or in infections of implanted medical devices, and bacteria protected within biofilms are much harder to kill than individual isolated bacteria.
What does bacteria use to adhere to surfaces?
A: biofilms

Context and question: The first fully attested complete translations of the Quran were done between the 10th and 12th centuries in Persian. The Samanid king, Mansur I (961-976), ordered a group of scholars from Khorasan to translate the Tafsir al-Tabari, originally in Arabic, into Persian. Later in the 11th century, one of the students of Abu Mansur Abdullah al-Ansari wrote a complete tafsir of the Quran in Persian. In the 12th century, Najm al-Din Abu Hafs al-Nasafi translated the Quran into Persian. The manuscripts of all three books have survived and have been published several times.[citation needed]
Who wrote a Persian translation of the Quran in the 11th century?
Answer: unanswerable

Question: There are more than 900 million Protestants worldwide,[ad] among approximately 2.4 billion Christians.[ae] In 2010, a total of more than 800 million included 300 million in Sub-Saharan Africa, 260 million in the Americas, 140 million in Asia-Pacific region, 100 million in Europe and 2 million in Middle East-North Africa. Protestants account for nearly forty percent of Christians worldwide and more than one tenth of the total human population. Various estimates put the percentage of Protestants in relation to the total number of world's Christians at 33%, 36%, 36.7%, and 40%, while in relation to the world's population at 11.6% and 13%.
Is there an answer to this question: What is the total population of Christians in the world?

Answer: approximately 2.4 billion

Question: Lossy data compression is the converse of lossless data compression. In these schemes, some loss of information is acceptable. Dropping nonessential detail from the data source can save storage space. Lossy data compression schemes are designed by research on how people perceive the data in question. For example, the human eye is more sensitive to subtle variations in luminance than it is to the variations in color. JPEG image compression works in part by rounding off nonessential bits of information. There is a corresponding trade-off between preserving information and reducing size. A number of popular compression formats exploit these perceptual differences, including those used in music files, images, and video.
Is there an answer to this question: What can save storage space?

Answer:
Dropping nonessential detail from the data source