【BIO】Biology Past Year Essay Question

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【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:53 am

Biology Past Year Essay Question ( chapter 1)





5/2005
(a) Describe briefly the primary, secondary and tertiary structures of
proteins. State the importance of these structures which are related to
the properties of protein.
[11]
(b) Give four types of proteins and their functions in living
organisms. [4]






Answer:
(a) Primary structure:
- sequences of amino acid in the polypeptide chain
- polypeptide chain consists of amino/ N-terminal and carboxyl/ C-terminal
- numbering of sequence starts from N-terminal
- the amino acids are linked by peptide bonds
- total amino acids/ R-group/ side chain/ functional group determine protein to be basic,
acidic or neutral/ soluble/ insoluble
Secondary structure:
- depends on hydrogen bonds
- produces α-helix and β-pleated structures
- α-helix give high elasticity/ cylindrical structure/ coiled in the helical structure
- β-pleated is for padding and cushion
- both structures may be present in a protein
Tertiary structure:
- depends on disulfide bridge/ bonds
- hydrophobic interaction/ bond, ionic bond and van der waals effect
- forming globular structure/ protein conformation/ folding
- 3-dimensional structure gives/ determines biological activity
- protein denaturation occurs when tertiary structure is broken/ destroyed

(b)
Types of proteins Function
Catalytic/ enzymatic To catalyse biological reactions
Transport To transport oxygen and carbon dioxide in blood circulation (haemoglobin)
To transport other substances to other part of the cells or within cells
Regulatory/ messenger/ hormone Coordination of cellular activities through messenger molecules (insulin)
Storage Storage for molecules required by the organism
(ovalbumin – storage for amino acid; calmodulin – storage for calcium;
ferritin – storage for iron)
Structural For support of organism (cocoon, hair, skin, keratin)
Immuno/ defence Protection against diseases (antibodies)
Receptor Response of cell to chemical stimuli
Contractile and motor For movement and mobility (actin and myosin)
Toxins Act as hydrolytic enzymes
Visual protein For vision


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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:53 am

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:53 am

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:54 am

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:54 am

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:54 am

Biology Past Year Essay Question ( chapter 9)




3/1994
(a) Dengan bantuan gambarajah yang berlabel, terangkan bagaimana
kehilangan air dapat dikawal melalui tindakan stoma pada daun
tumbuhan.
[8]
(b) Terangkan fungsi ginjal sebagai organ homeostasis. [4]
(c) Jelaskan mengapa seseorang yang kehausan tidak mengeluarkan kencing. [6]

Jawapan:
(a) Tindakan stoma daun:
- pembukaan dan penutupan stoma dikawal oleh sepasang sel pengawal
- gambarajah stoma yang berlabel
- kehilangan air dicegah melalui penutupan stoma
- perubahan kesegahan sel pengawal mempengaruhi saiz stoma
- sel pengawal bentuk ginjal/ kekacang
- dinding sel tak sama tebal/ lebih tebal pada dinding dalam
- waktu siang, fotosintesis berlaku, kepekatan gula tinggi/ tekanan osmosis tinggi
- air masuk ke dalam sel pengawal dari sel-sel di sekeliling
- menyebabkan kesegahan sel yang tinggi
- dinding sel yang nipis tertolak keluar dan menarik dinding tebal
- lalu stoma terbuka
- waktu malam, kepekatan gula rendah/ tekanan osmosis rendah
- sel pengawal kurang segah/ flasid daun stoma tertutup

(b) Fungsi ginjal:
- mengawalatur keseimbangan air/ tekanan osmosis
- melalui pengawalan kadar penyerapan semula air
- mengawalatur bahan larut seperti glukosa/ asid amino/ ion
- melalui penyerapan aktif
- mengawal pH darah/ pH bendalir
- melalui kawalan [H+]
- membuang bahan toksik/ urea/ bahan kumuh

(c) - tekanan osmosis darah menjadi tinggi bila haus
- merangsang osmoreseptor di otak/ hipotalamus
- hormon anti diuretik/ ADH dirembes
- dari kelenjar pituitari posterior
- melalui darah ke ginjal
- meningkatkan ketelapan tubul ginjal/ tubul pengumpul
- untuk menambahkan penyerapan semula air
- sehingga tekanan osmosis darah diturunkan semula/ kembali normal

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:54 am

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周六 七月 25, 2009 11:54 am

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 lonelytree 于 周三 七月 29, 2009 8:26 am

我需要这个。。谢谢啊。。

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周四 七月 30, 2009 4:27 am

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~
I love you

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 lonelytree 于 周四 七月 30, 2009 7:02 am

拿去给我老师,叫他翻译算了。。 Sad

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 Giraffe 于 周日 八月 02, 2009 12:34 am

lonelytree 写道::拿去给我老师,叫他翻译算了。。 Sad

欺负老师呀 scratch

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

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回复: 【BIO】Biology Past Year Essay Question

帖子 由 lonelytree 于 周一 八月 03, 2009 2:52 am

因为我都不知道我的老师在教什么。。。问他比较容易 Twisted Evil

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