動物
Animal

context: zh_tw: 所有的動物都有真核細胞，且被包在由膠原蛋白和具彈性的糖蛋白所組成的獨特細胞外網路之中。這些網路或許會鈣化以形成甲殼、骨頭和針骨等結構。在發育時會形成一個較可變動的架構，好讓細胞能移動且被重新組織，好使得複雜的結構變得可能。相對地，其他如植物和真菌等多細胞生物有被細胞壁固定住位置的細胞，所以以漸進的生長方式來發育。另外，動物細胞特有的還有如下幾種細胞間的結合：緊密接合、間隙接合和橋粒。
en: All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible. This may be calcified, forming structures such as shells, bones, and spicules. In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, and desmosomes.With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues. These include muscles, which enable locomotion, and nerve tissues, which transmit signals and coordinate the body. Typically, there is also an internal digestive chamber with either one opening (in Ctenophora, Cnidaria, and flatworms) or two openings (in most bilaterians).
qas: question: zh_tw: 在動物中形成的額外細胞基質可以由什麼組成？
en: the extra cellular matrix forms in animals and can be composed of what?
answers: zh_tw: text: 膠原蛋白和具彈性的糖蛋白
en: text: collagen and elastic glycoproteins

context: zh_tw: 幾乎所有的動物都會進行某種型別的有性生殖。成熟的個體是雙倍體或多倍體的。牠們有一些特化的生殖細胞，行減數分裂以產生較小可遊動的精子或較大不可動的卵子。精子和卵子會結合成為受精卵，且發育成新的個體。
en: Nearly all animals make use of some form of sexual reproduction. They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova. These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge. In most other groups, the blastula  undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm, also develops between them. These germ layers then differentiate to form tissues and organs.Repeated instances of mating with a close relative during sexual reproduction generally leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren (Malurus splendens), females benefit by mating with multiple males, thus producing more offspring of higher genetic quality.Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. This may take place through fragmentation; budding, such as in Hydra and other cnidarians; or parthenogenesis, where fertile eggs are produced without mating, such as in aphids.
qas: question: zh_tw: 大多數動物是如何繁殖的？
en: How do most animals reproduce?
answers: zh_tw: text: 有性生殖
en: text: sexual reproduction