Here is a question about this article: The avian circulatory system is driven by a four-chambered, myogenic heart contained in a fibrous pericardial sac. This pericardial sac is filled with a serous fluid for lubrication. The heart itself is divided into a right and left half, each with an atrium and ventricle. The atrium and ventricles of each side are separated by atrioventricular valves which prevent back flow from one chamber to the next during contraction. Being myogenic, the heart's pace is maintained by pacemaker cells found in the sinoatrial node, located on the right atrium. The sinoatrial node uses calcium to cause a depolarizing signal transduction pathway from the atrium through right and left atrioventricular bundle which communicates contraction to the ventricles. The avian heart also consists of muscular arches that are made up of thick bundles of muscular layers. Much like a mammalian heart, the avian heart is composed of endocardial, myocardial and epicardial layers. The atrium walls tend to be thinner than the ventricle walls, due to the intense ventricular contraction used to pump oxygenated blood throughout the body. Avian hearts are generally larger than mammalian hearts when compared to body mass. This adaptation allows more blood to be pumped to meet the high metabolic need associated with flight.
What is the answer to this question: Where is the heart contained in the avian circulatory system?
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So... fibrous pericardial sac

Here is a question about this article: The Sun remained loyal to Thatcher right up to her resignation in November 1990, despite the party's fall in popularity over the previous year following the introduction of the Poll tax (officially known as the Community Charge). This change to the way local government is funded was vociferously supported by the newspaper, despite widespread opposition, (some from Conservative MPs), which is seen as having contributed to Thatcher's own downfall. The tax was quickly repealed by her successor John Major, whom The Sun initially supported enthusiastically, believing he was a radical Thatcherite despite the economy having entered recession at this time.
What is the answer to this question: When did Margaret Thatcher leave office?
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So... November 1990

Here is a question about this article: Political parties, still called factions by some, especially those in the governmental apparatus, are lobbied vigorously by organizations, businesses and special interest groups such as trade unions. Money and gifts-in-kind to a party, or its leading members, may be offered as incentives. Such donations are the traditional source of funding for all right-of-centre cadre parties. Starting in the late 19th century these parties were opposed by the newly founded left-of-centre workers' parties. They started a new party type, the mass membership party, and a new source of political fundraising, membership dues.
What is the answer to this question: Around which time was the mass membership party started?
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So...
19th century