转基因的热议到靶向药物对癌症的治疗
从基因编辑婴儿的伦理问题
到大脑研究对人工智能的促进
生物离人们的生活越来越近
也越来越吸引同学们进行学习和研究
除了生物专业以外
很多英国大学热门的医学以及心理学专业
也会要求学生进行A-Level生物的学习
A-Level生物可以分为AS和A2两个不同Level的考试。
以Edexcel考试局为例,AS和A2分别为3个单元的测试,一共6次考试需要参加。
Unit 1、Unit 2、Unit 3是AS的考试,卷面满分分别为80、80、50,最后折算为120、120、60满分的相应成绩计入最后的总分之中;
Unit 4、Unit 5、Unit 6则是A2的考试,卷面满分分别为90、90、50,也一样最后折算为120、120、60满分的相应成绩计入总分之中。
最终的总分为600分满分,达到480分为A,420为B,以此类推。而A*的要求为在达到A(480分)基础之上,A2的3个单元,也就是Unit 4、Unit 5、Unit 6的总分要达到270分以上。
在19年10月考季中
想不想知道A-Level生物都考察了哪些知识点
接下来该如何准备1月的考试
下面我们一起跟着锦秋生物组老师
通过回顾A-Level生物U1、U2十月考情分析
整理出2020年1月考试备考方向
(b) Calculation
2. Genetic analysis
(a) Genetic diagram Punnett square or pedigree

XAXa is not affected
Male have only one X chromosome, therefore the heterozygote of Xa will directly lead to the disorder(XaY)
4. Carbohydrate and experimental design
(i) B
(ii) bond to join monosaccharide to disaccharide: glycosidic bond
(iii) describe the result
General trend+ extreme value + use of figure
(iv) experimental design :
Control the variables (EX. the concentration )+ digitalize the sweetness( use a figure from 0-5 to record the sweetness)+wide sample( have more than 100 volunteer)+ proper intervals between tasting 2 samples( prevent the lack of sensitivity)
(c) Similarity and difference between amylose and amylopectin
S:monomer
D:Branches/bond/terminals/rate of hydrolysis
5. Transport across the membrane
Active transport/Facilitated diffusion
Similarity:Use protein, transport polar molecules
Difference:Direction and the energy use
(a) the difference of active transport and Diffusion
L: diffusion K:Active transport
(i)Temperature can change the Rate of diffusion
(C) (i)Fluidity of membrane and phospholipid bilayer
(ii) Surface area to volume ratio and the rate of diffusion
6. DNA and genetic code
(a) Check the code table and line the amino acid according to the code
(b) Substitution/deletion/addition
(ii)Degenerated code+ meaningful mutation: change the Amino Acid chain/stop the chain early——change the primary structure of protein
7. Blood pressure and artery structure
(a) (i) calculation of the difference of Diastolic pressure and Systolic pressure
(ii)Calculation of MAP :pay attention to the indication of elastic artery
(iii) Artery pressure too low—— lead to the low force and the low pressure in artery—— slower blood flow—— rate of Gas exchange(O2)/CO2) ——Tissue exhauseted for anaerobic respiration
(b) (i) Calculation with reduction of a fraction
(i) C
(ii) Smooth endothelium to reduce the friction
(c) (i) Thick wall to withstand the pressure and elastic fibre to stretch and recoil
(ii) CVD and the elastic fibre_atherosclerosis
8. The amino acid cycle
(a) The structure of amino acid
(b) Specificity of enzyme
(c) (i) According to the cycle , citrulline will be less, ornithine will be excessive, and carbamyl phosphate will be excessive
(ii) the vesicle fuse with then cell and transmit the mRNA that code for OTC to the cell ,attaching to the ribosome and transcribed into Enzyme.




controlling the production of {enzymes / protein} ;
enzymes being {produced / released / secreted
enzymes being used to {digest / break down (tissues of style ;
idea of forming a pathway through style to embryo sac
For sperm to reach the egg cell and fertilaize the egg and the polar bodies
(d) Describe the outcome of a research
Describe Bar chart:
(1) general trend ( negative correlation but not linear )
(2) extreme value
(3) Use data
(ii) Describe the main composition of the middle lamella
The Verapamil will inhibbit the uptake of Ca2+
Pectin + Ca2+→Calcium Pectate in middle lamella
Calcium Pectate bind to cellulose of primary cell wall , stablizing the cell wall
Verapamil will weaken the cell wall by reducing the Calcium Pectate forming
Separate adjacent cells
5. 主考点:Medicine testing and Minerals in plant
(a)Nitrogen in plant:DNA synthesis(base)/Protein synthesis(amino group in amino acid)
(b)secretory protein and involved organelles
Golgi apparatus:
This enzyme is secretory protein
Modify/add(reduce)carbohydrate chain(group)to protein/enzyme
Transport protein (enzyme)/form/vesicle to Membrane
(c)Drug test :
Test on healthy animal(rabbits or mice)/animal infected with the diseases
Phase 1 Test on healthy Volunteers : check on The Harmful side effects and safe dosage for human
Phase 2 : Test on a small group of healthy volunteers or volunteers with disease, covering different gender and age: check on the effectiveness
Phase 3 : Test on a small group of healthy volunteers or volunteers with disease, covering different gender and age: check on the effectiveness
6. Evolution and adaption
(a) The definition of endemism(B)
(b) The difference of anatomical,physiological and behavioral adaption
Anatomical/physiological /anatomical adaption
(c) Discuss the advantage of adaption according to the given material
Repel the predator by producing poison
threaten the predator by bright color and spot on the skin
Adhesive disc on toes to facilitate moving and climbing
(d) The natural selection and Hardy-Weinbergg equasion
With the selection pressure(predator hunting)
New mutation coming out
Individuals with advanced Mutation (producing poison)survive/Individuals without this advantage are hunted
Individuals with advanced Mutation have the opportunity to give rise to offsprings
The gene pool changes , the frequency of the mutated gene increases, and that of gene without mutation decrease
More frog can produce poison
7. 主考点:Plant based material
(a) Properties of Lignin
(i)Waterproof give tensile strength
(ii)Similarities and differences of sclerenchyma and xylem
Similarity:
Dead cell without cytoplasm
Secondary cell wall with elastic fibre
Difference
Sclerenchyma: thicker wall, support the stems and leaves
Xylem: supply water /mineral ions and support the leaves and stems
(b) Sustainabity
Renewable material can be can be regrown in short time
Can be broken down biologically
Cause no pollution
(c)
(i) Calculation based on a constant increasing rate
(ii) Describe and analyze the given diagram
Possible outcome
Advantages:
Those plants can be regrown fast, renewble
After being burned, only CO2 is released, causes no pollution
And the biofuel can be biologically broken down
Some biofuel can release less CO2 producing the same amount of energy( hemp:12)
Disadvantages:
Biofuel (especially biodiesel) can release more CO2
CO2 release: Soybean(49)>Sugar beet(40)> rapeseed(37)
The production of the material can consume water , fertilisers, pesticides
Fertiliser and pesticide are not environmentally
Can cause pollution to the soil and water
Water: producing Biodiesel can use more water Rapseed, soybean > hemp and sugar beet
Fertilizer:Sugar beet>Rapeseed>soybean >hemp
Pestiside:Sugar beet,Rapeseed,soybean>hemp(with figure)
Conclusion:hemp consumes less resource to produce,release less CO2 when burning
Soybean consumes more resource to produce, release more CO2
8. 主考点:Gene expression
(a) Structure of the sperm
C (not asking where the acrosomal enzyme stores)
(b) Embryo development
Morula( formed after cell division of zygote, not differentiated)
(c) Differentiation
(i) Epigenetic modification
Histone methylation and acetylation/DNA methylation and demethylation/RNA splicing/transcriptional factors
(ii) Switching on/off the gene
Through Histone/DNA methylation,some gene is switched off/active,and can not be expressed。
Through Histone acetylation/DNA demethylation, some gene is switched on/inactive, and can be expressed.
Transcription factors regulation:bind to the enhancer can increase the rate of expression
Transcription and translation into protein (enzyme) can be regulated
Cell can have different structure,can carry out different function(e.g. red blood cell :haemoglobin,carry oxygen)
Permanently modifies cell
The effect of environment on gene expression
Alleles : C,Cch,Ch,ca
C is dominant to Cch, ca
Ch is dominant to ca
C code for normal tyrosinase, can catalyse the forming of melanin
Ch is a recessive mutation of C, code for a mutation of tyrosinase, which can only be active in low temperature
Skin on nose , ears legs and claws are in low temperature because they emit the heat by producing liquid and increase of surface
The a mutation of tyrosinase is active in these area, so the skin can produce the melanin, the fur is black, in other area, the tyrosinase denatures, the fur is white.
ca code for inactive tyrosinase, can not catalyse the formation of melanin
The genotype and environment can both determine the phenotype(the fur color)