關(guān)于2022夏季GCSE、AS和A-Level考試成績說明！
近日，英國資格與考試監(jiān)督管理辦公室（ofqual）發(fā)布最新通知：《關(guān)于2022夏季GCSE、AS和A-Level考試成績說明》。 圖源：英國政府網(wǎng) 1，ofqual：2022夏季考試成績說明 1、2022年夏季考試，考試委員采用的評分方法...
IB DP Biology: HL復(fù)習(xí)筆記11.1.2 Specific Immune Response
Specific Immune Response T-Helper cells (a type of lymphocyte that responds to specific antigens) and mature?B cells?(another type of lymphocyte) have specific receptors located on their cell surfa...
IB DP Biology: HL復(fù)習(xí)筆記11.1.1 Antigens
Antigens Every organism has cells with?unique molecules?on the cell surface membrane which act as?markers?to?identify?it These unique markers are?macromolecules?and they allow?cell-to-cell recognit...
IB DP Biology: HL復(fù)習(xí)筆記10.3.5 Skills: Comparing Allele Frequencies Between Populations
Populations & their Allele Frequencies Comparison of allele frequencies of geographically isolated populations Allele frequency is a term that assigns a?relative frequency?of an allele at a par...
IB DP Biology: HL復(fù)習(xí)筆記10.3.4 Polyploidy & Speciation
Polyploidy & Speciation NOS: Looking for patterns, trends and discrepancies—patterns of chromosome number in some genera can be explained by speciation due to polyploidy When patterns and trend...
IB DP Biology: HL復(fù)習(xí)筆記10.3.3 Speciation
Gradualism & Speciation Speciation can be defined as the emergence of new and distinct species that are reproductively isolated from other separate species Two theories exist to explain the eme...
IB DP Biology: HL復(fù)習(xí)筆記10.3.2 Evolution
The Process of Evolution by Natural Selection Evolution requires that?allele frequencies change?with time in populations Evolution is defined as the?cumulative change in the heritable characteristi...
IB DP Biology: HL復(fù)習(xí)筆記10.3.1 Gene Pools
Gene Pools A gene pool consists of all the genes and their different alleles, present in an interbreeding?population Some populations of the same species are geographically isolated from each other...
IB DP Biology: HL復(fù)習(xí)筆記10.2.6 Variation
Types of Variation The ways in which organisms differ from one another is called?variation Variation occurs?between species In fact, species are classified based on differences between their respec...
