Edexcel IGCSE Biology Paper 2 - Last Minute Tips!

Hazel goes through her last minute tips to help you prepare for the upcoming Edexcel IGCSE biology paper 2 exam (2B)

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These SwH Learning videos are designed to help with your GCSE or IGCSE science revision.

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Hazel completed her undergraduate degree at St John's College, the University of Cambridge. She then did a PGCE (Post-Graduate Certificate of Education) before qualifying as a science teacher. She now works full time as a professional tutor.

Material required for Grade 9 (A*) is included.

Please leave any topic requests in the comments below.

[mnmill]

Notes I made from the video with a bit of detail..

The long passage based question to be done last as you will have more time at the end to actually read it properly. Majority of times, the answer/s is from your own knowledge, if any calculation based question/s come up, data can be obtained from the passage. Underline any information that you feel is of importance and could help in building and framing your answer/s

Protein synthesis
Transcription
- Occurs in the nucleus
- Part of the DNA unwinds
- Bases are exposed along the template strand
- Network forms upon which mRNA molecule forms
- Building blocks of mRNA: RNA nucleotides
- RNA nucleotides pair up with template strand bases according to the complementary base pairing rule
- mRNA strand forms, leaves nucleus

Translation
- Takes place in cytoplasm
- Ribosome moves along with the mRNA strand
- mRNA attaches to the ribosome
- tRNA brings amino acids to the ribosome
- mRNA codon binds with the complementary anticodon on the tRNA producing an amino acid chain and forms polypeptide bonds
- At the end of the chain there will be a stop codon that ends translation

Mutation
- Random rare change in a DNA

If addition/deletion of base
- Different sequence of amino acid brought to the ribosome
- Give a different protein with a different phenotype

Substitution
- May not be a change in amino acid sequence
- May have the same protein with the same phenotype

Effect of pH on enzyme activity
Amylase digests starch -> glucose
Iodine blue black in the presence of starch
Orange in the presence of glucose
Benedicts blue
Brick red in the presence of glucose

Nitrogen cycle

- Nitrates absorbed by root hair cells by active transport from an area of low concentration -> high concentration against the - concentration and uses energy from ATP
- Plants use the nitrates to make proteins (amino acids) + growth (assimilation)
- Plants eaten by animals (assimilation)
- Animal and plants die and they are decayed by decomposers (fungi or bacteria) and this converts nitrates -> ammonia
- Nitrifying bacteria converts ammonium ions -> nitrites then nitrates
- Denitrifying bacteria converts nitrates -> nitrogen gas
- Nitrogen fixing bacteria found in root nodules converts the nitrogen gas -> nitrates. Nitrogen fixation happens with lightning as well.

Kidney

Order of the different parts of the nephron
Glomerulus -> Bowman's capsule -> PCT -> Loop of Henle -> DCT -> Collecting duct

Excretion of urea
- Ultrafiltration
- Occurs in glomerulus
- ions, water, glucose, and urea enters the bowman’s capsule
- Selective reabsorption takes place in PCT where glucose is reabsorbed back into the blood by active transport
- Presence of proteins in urine (due to damage to bowman’s capsule)
- Proteins are too large to enter.
- Presence of glucose (PCT not working)

Osmoregulation
- Osmoreceptors in the hypothalamus detects low water level
- Stimulates pituitary gland to release ADH
- This ADH acts on the walls of the collecting duct, making them more permeable so more water is reabsorbed back into the blood
- Urine is less in volume and more concentrated and yellow

FSH and LH from pituitary gland

FSH
- matures the egg
- stimulates follicle growth
- stimulates egg development
- stimulates sperm production in males
- stimulates oestrogen secretion

LH
- stimulates ovulation (egg release) (peaks)
- stimulates production of testosterone
- stimulates development of corpus luteum
- Stimulates testosterone production in males

[lovemaroon-hdxk]

Good luck everybody! Lets smash it!!!😄

[vmaiks]

could you please make a predicted video

[a.k.s]

can you please do a prediction video miss pleasee, you're videos have acc helped me so much in biology esp the vid on how to answer long answer question like "discuss" or "Comment" i've always struggled on those so thank youu

[sprawlsreadsking]

Hi miss can you please do one for paper 2 physics it's tomorrow

[dinomaster]

Does the paper 2 also contain double science content?

[loidapascua]

Can you make a power point with picture and defination to understand easily .Thanks so much ❤

[Ellasnaps]

Is this for higher specifically or foundation?