【BIO】Biology Past Year Essay Question

5/2006
(a) Describe four properties which render water to be an important medium for life. [8]
(b) Describe the importance of water soluble vitamins in human metabolism. [7 ]
Answer:
• Solvent
• water is a polar/bipolar/charged molecule
• solubilizes most of biological molecules/medium for biological reaction/ionic solids/nutrient substances
• due to the hydrogen bonding

• high heat capacity/high latent heat of vapourisation
• good in maintaining against temperature fluctuation/stabilize temperature
• high boiling point
• evaporation leads to cooling effect

• high su***ce tension
• formation of plasma membrane/micelle
• cohesion and adhesion forces for movement of water up a capillary

• maximum density of water at 40C/ice float on water
• water increases in volume and reduces in density as temperature drops
• this ensure aquatic organisms to survive in freezing water/ice is an insulator of heat

• low viscosity
• acts as lubricant //low resistant for movement

(b)
• Water soluble vitamins are vitamin B complex and vitamin C/ascorbic acid
vitamin C/ascorbic acid :
• anti-scurvy
• coenzyme
• antioxidant/detoxification

Vitamin B
• B1/thiamine – helps release energy from carbohydrate/decarboxylation
• B2/riboflavin – component of FAD and FMN/ coenzyme
• B3/niacin/nicotinic acid – component of NAD+ and NADP+
• B5/panthotenic acid – component of coenzyme A
• B6/pyridoxine – coenzyme in amino acid/protein metabolism//transamination
• B12/cobalamine/cyanocobalamine – coenzyme in nucleic acid metabolism//maturation of red blood cell
• Biotin – coenzyme in metabolism
• Folic acid/folate – coenzyme in nucleic acid and protein metabolism//formation of red blood cell

Biology Past Year Essay Question ( chapter 2)





6/2003
(a) Draw and label the structure of a cell membrane based on Singer’s model. [2]
(b) Explain the roles of the structures of the cell membrane in the transportation of substances into the cell. [13]
Answer:
(a) Rajah betul – dwilapisan fosfolipid
- protein integral/ intrinsik merentasi dwilapisan
Label – dwilapisan fosfolipid dan protein integral/ intrinsik// protein periferal/ ekstrinsik

(b) Fosfolipid/ dwilapisan fosfolipid:
- membenarkan bahan larut lemak merentasi membran
- contoh: vitamin/ gliserol/ asid lemak/ kolesterol/ hormon steroid
- dinamik/ bergerak
- secara endositosis/ fagositosis dan pinositosis
- bertaup membentuk vesikel makanan
- contoh: makromolekul/ protein
Liang seni/ ruang antara molekul fosfolipid:
- membenarkan molekul kecil dan tidak bercas/ bercas positif/ berkutub melaluinya
- contoh: air/ oksigen/ CO2
Protein integral/ intrinsik:
- sebagai protein pembawa/ terusan
- mengangkut bahan secara resapan berkemudahan
- melalui perubahan konformasi protein/ atau melalui terusan
- contoh: glukosa/ air/ ion-ion
- tidak memerlukan tanaga/ pasif
- pengangkutan juga boleh berlaku secara aktif/ perlu tenaga (ATP)
- melawan kecerunan kepekatan
- contoh: ion Na+ dan K+
Protein periferal/ ekstrinsik:
- sebagai protein reseptor
- bahan bergabung pada tapak protein reseptor
- merangsang pembukaan terusan/ meningkatkan ketelapan membran
- contoh: ion Na+ yang masuk membran pos/ pasca-sinaps

Biology Past Year Essay Question ( chapter 24)





9/2005
(a) What is meant by species?
(b) Explain the problems that exist in defining species.
(c) Explain how different species could maintain their identities through the isolating
mechanism.

Answer:
(a) - species consists of one or more populations/ a group of individuals
- whose members show high similarity in morphological characters// can interbreed
producing viable fertile offspring
- but different from members of other population/ species// but not with members of
othe population/ species

(b) - this concept is based solely on morphological features
- variation within the species does exist
- members of different populations interbreed/ hybridize
- members reproduce a***ually
- polymorphism/ ***ual dimorphism/ different form in their life cycle
- biological species concept cannot apply for fossil organism/ herbarium materials/
museum materials
- lack of experimental evidence

(c) - prezygotic isolating mechanism
- ecological/ habitat isolation:
# different species reproduce in different habitats
- behavioral isolation:
# different species have distinct courtship behavior
- mechanical isolation:
# different species have structural differences in their reproductive organs
- gametic isolation:
# gametes of different species are genetically incompatible
- temporal isolation:
# different species reproduce/ flower at different times

- postzygotic isolating mechanism
- hybrid inviability:
# different hybrid dies at early stage of embryonic development
- hybrid sterility:
# interspecies hybrid survive to adulthood/ not fertile
- hybrid breakdown:
# offsprings of interspecific hybrids unable to reproduce successfully

Biology Past Year Essay Question ( chapter 12)





7/2006
(a) Explain how active immunity is acquired through humoral response. [10]
(b) State one function of each type of the following cells.
(i) Plasma cell
(ii) Helper T cell
(iii) Macrophage
(iv) Cytotoxic T cell
(v) Suppressor T cell [5]

(a) - bacteria /virus/pathogen/antigen infect/invade body
- B cell/macrophage/APC recognises the antigen of the bacteria/virus/pathogen
- B cell/ macrophage/APC processes/engulf/digest the bacteria/virus/pathogen
- attaches antigen to MHC protein and displayed/exposed/presented on the su***ce of B cells /macrophage/APC
- helper T cells bind to antigen-MHC complexes on B cells/macrophage
- helper T cells become activated
- helper T cells produce interleukin-2/cytokines
- initiate B cells to divide rapidly/produce clones
- by the clonal selection
- to form plasma cells and memory cells
- plasma cells produce antibody
- memory cells will initiate production of plasma cells
when encounter the same bacteria/antigen in future infection
- the immunity is long lasting
- the antibody is specific for a particular bacteria/virus/patogen

(b)
Type of cell Function
Plasma cell - secretes/forms/produces/releases antibodies
Helper T cell - activates B cells//stimulates cytotoxic T cells
Macrophages - ingest/digest/process/engulf bacteria/pathogen/virus//acts as antigen-presenting cells/APC
Cytotoxic T cell - destroys virus-infected/cancerous/other altered body cells
Suppressor T cell - suppresses the immune response/T and B lymphocytes

Biology Past Year Essay Question ( chapter 5)





3/1998
(a) Apakah yang dimaksudkan dengan ATP? Jelaskan bagaimana sebatian
ini bertindak sebagai sumber tenaga dalam sistem biologi.

[8]
(b) Pemecahan satu molekul glukosa secara aerob menghasilkan
sebilangan ATP, karbon dioksida dan air. Huraikan
peringkat-peringkat di mana pembentukan ATP berlaku semasa
pemecahan molekul glukosa itu. (Perincian tentang glikolisis dan kitar
Krebs tidak diperlukan).
[12]

(a) ATP:
- adenosin trifosfat
- gabungan bes adenine, gula ribosa dan kumpulan fosfat
- mempunyai ikatan fosfat bertenaga tinggi
- bila ikatan terurai menghasilkan tenaga segera
- semasa hidrolisis
- ATP dipecahkan kpd ADP + Pi
- melibatkan enzim ATPase
- menghasilkan 30-34 kJ tenaga

(b) peringkat-peringkat dimana pembentukkan ATP berlaku semasa pemecahan molekul glukosa:
- pembentukkan ATP bermula ketika glikolisis dalam sitoplasma
- sebatian PGAL menjadi asid piruvik
- ATP terhasil melalui pemfosforilan peringkat substrat bersama NADH
- NADH memasuki sistem pengangkutan elektron dalam mitokondrion
- menghasilkan ATP
- setiap asid piruvik mengalami dekarboksilasi dalam mitokondrion
- menjadi asetil koA dan H terbebas, diterima oleh NAD+ membentuk NADH/3ATP dihasilkan
- asetil koA memasuki kitar Krebs
- menghasilkan asid sitrik yg akan ditukarkan kpd sebatian 5-C/α-ketoglutarat
- NADH/3 ATP dihasilkan
- sebatian 5C menjadi suksinat (4C)
- menghasilkan 1 GTP/ATP dan NADH/3ATP
- suksinat menjadi fumarat
- menghasilkan 1 FADH2 /2 ATP
- fumarat ditukar kpd malat, kemudian ke oksaloasetik asid
- menghasilkan 1NADH/3ATP
- keselurohannya 1 molekul glukosa menghasilkan 36/38 ATP

5/2004
(a) Describe the main stages of the Krebs cycle. [9]
(b) Cyanide is a deadly poison and forms a complex with cytochrome a3.
How does this poison affect cellular respiration?

[6]

(a) the main stages of Krebs cycle:
- acetyl Co-A(2C fragment) is added to oxaloacetate (4C) producing citrate(6C)
- citrate undergoes decarboxylation/loses a CO2 molecule
- and oxidized/dehydrogenated to form α-ketoglutarate(5C)
- while reducing NAD+ to NADH/NADH is formed
- α-ketoglutarate undergoes decarboxylation /loses a CO2 molecule
- and oxidized to form succinate(4C)
- one molecule of NADH is formed/NAD+ is reduced to NADH
- one molecule of GTP is formed by substrate level phosphorylation
- succinate is oxidized to fumarate
- FAD is reduced to FADH2
- fumarate is hydrated to form malate(4C)
- malate is oxidized to regenerate oxaloacetate
- while reducing NAD+ to NADH

(b) how cyanide affects cellular respiration:
- cyanide inhibits cytochrome oxidase
- prevents transfer of electrons from cytochrome a3 to oxygen
- no proton gradient will be established/no chemiosmosis
- stopping ATP production
- NADH not oxidized to NAD+
- no oxidation of pyruvic acid to acetyl coA
- FADH2 not oxidised to FAD
- NAD+ and FAD are not available to accept electrons for oxidation in the Krebs cycle
- causing cellular respiration in mitochondria to come to a halt











韩冰

我需要这个。。谢谢啊。。

lonelytree 写道:我需要这个。。谢谢啊。。

不用客气呀~
只是有些是马来文版本的，需要自己翻译一下咯~

拿去给我老师，叫他翻译算了。。

lonelytree 写道:拿去给我老师，叫他翻译算了。。

欺负老师呀

可是，我的老师都好像不太愿意为我们解答问题的呢。。
你老师真好~ T.T

因为我都不知道我的老师在教什么。。。问他比较容易