SAT2生物考试专业词汇：N.

　　SAT2考试是SAT subject test的通常说法，SAT2考试有别于SAT1，它是一种专项考试，考察学生某一科目的能力。下面澳际小编搜集整理了SAT2生物考试专业词汇中以字母N打头的词汇，希望能够帮助大家更好地备考SAT2生物考试。

　　NADH

　　An energy-carrying coenzyme produced by glycolysis and the Krebs cycle. NADH carries energy to the electron transport chain, where it is stored in ATP.

　　natural selection(自然选择)

　　The theory, first proposed by Darwin, which holds that organisms produce as many offspring as possible, which compete for limited resources. Organisms’ characteristics vary, and certain characteristics will allow organisms to survive and reproduce more fectively. These adaptive characteristics will be more prevalent in subsequent generations. Natural selection is the engine of evolution, choosing the most fit genes to pass from one generation to the next.

　　Notochord(脊索)

　　A longitudinal rod of cells that forms in the least developed chordates and in embryonic stages of more developed chordates.

　　Nucleolus(核仁)

　　A dense, spherical body inside the nucleus of a cell. The nucleolus makes the RNA that is a structural component of the ribosomes.

　　Nucleotide(核苷酸)

　　The monomer of a nucl acid. Nucleotides consist of (1) a phosphate group, a group of atoms containing phosphorus; (2) a sugar; and (3) a nitrogenous base, a compound containing nitrogen that removes H+ ions from solution. Nucleotides are grouped into two general classes, depending on the sugar group that they carry: deoxyribonucl acids (DNA) contain the sugar deoxyribose and ribonucl acids (RNA) contain the sugar ribose. Nucleotides are further divided by the type of nitrogenous base that they carry. DNA is composed of adenine, thymine, guanine, and cytosine. RNA is composed of adenine, uracil, guanine, and cytosine.

　　Nucleus(细胞核)

　　The large, central organelle of eukaryotes. The nucleus contains the genetic material of the cell and controls cellular activities.

　　Nephridium(肾管)

　　A blood filtration and excretory organ characteristic of segmented worms.

　　Nephron(肾单位) ：肾的解剖与功能单位,包括肾小球等

　　Tiny, tubule structures responsible for the filtering of blood in the kidneys of vertebrates.

　　neritic zone(浅海水层)

　　The medium depth zone of the marine biome. Extends to 600 feet beneath the water’s surface and sits on the continental shelf, hundreds of miles from any shore. Algae, crustaceans, and fish inhabit this region.

　　nervous system(神经系统)

　　Control system of the body that functions by sending impulses through neurons to receive information and spur muscles to action.

　　Neuron(神经元)

　　The functional unit of the nervous system. A neuron is a specialized cell able to carry an action potential and made up of dendrites, a cell body, and an axon. There are three types of neurons: sensory, motor, and interneurons.

　　Niche(生态龛)

　　The unique role a population plays in a community. A niche includes all characteristics that dine the way a population exists in a community, from where the members live to what they eat, when they sleep, and how they reproduce.

　　nitrogenous base(含氮碱基)

　　One of the nitrogen-containing bases in DNA and RNA nucleotides. There are five nitrogenous bases in living organisms. DNA is composed of adenine, thymine, guanine, and cytosine. RNA is composed of adenine, uracil, guanine, and cytosine.

　　Nondisjunction(不分离)：细胞分裂时成对的染色体无法分开

　　Occurs when a pair of homologous chromosomes fails to separate during gamete formation. The offspring produced from these gametes have either one too many or one too few of a particular chromosome. Nondisjunction is the cause of genetic disorders such as Down syndrome.

　　以上便是澳际小编为大家整理的SAT2生物考试专业词汇中以字母N打头的词汇的相关介绍，希望对大家有所帮助。更多SAT考试相关资料尽在澳际教育网SAT考试频道，澳际小编祝大家都能取得理想的SAT2生物考试成绩!