Phenotypes The?observable characteristics?of an organism are its?phenotype Phenotypic variation?is the difference in phenotypes between organisms of the same species In some cases, phenotypic varia...
Epigenetics An organism’s internal or external?environment?can?influence gene expression?patterns The levels of?regulatory proteins?or?transcription factors?can be affected in response to?environme...
Cell Differentiation Stem cells?become?specialised?through?differential gene expression This means that only certain genes in the DNA of the stem cell are?activated?and get?expressed Every nucleus ...
Stem Cells in Medicine As stem cells have the ability to?differentiate?into other?specialised cell types, they are very?valuable?in?medical research and treatments?as they have the potential to?rep...
Stem Cells A?stem cell?is a cell that can divide (by mitosis) an unlimited number of times Each new cell (produced when a stem cell divides) has the potential to remain a stem cell or to develop in...
Meiosis: Source of Genetic Variation Meiosis gives rise to cells that are?genetically different?from each other and is the type of cell division used to produce?gametes?(sex cells) During meiosis, ...
Locations of Genes on a Chromosome Every?chromosome?consists of a long DNA molecule that contains several hundred or even thousands of?different genes?coding for different proteins A length of DNA ...
Fertilisation in Mammals During sexual intercourse, semen is ejaculated high up into the?vagina?of the female,?near the cervix The sperm cells then follow a?chemical trail released by the egg cell?...
2023香港AP報名截止時間延長，新增考位名額今日起報名！香港AP考場一直是大陸社會考生的首選項，所以10月香港開放報名后很快滿額，中間增加過一次名額，但似乎依舊供不應(yīng)求。 重點如下： 1、報名時間：11月9日上...
