2. Cell Biology 细胞生物学
USABO
everything else is directly bound by
a phospholipid bilayer
Peroxisome: fatty acid metabolism,
detoxification, H2O2 metabolism
• Antibiotics mainly work on bacteria;
• Prokaryotes have no membrane bound organelles;
• Streptomycin binds directly to small subunit of ribosomes
Antibiotics act on bacteria through specific mechanisms,
inhibiting their growth or directly killing them. Different
antibiotics act on different parts or processes of bacteria, mainly
in the following ways:
1. Inhibit cell wall synthesis (e.g., penicillin, amoxicillin)
2. Destroy cell membrane structure (e.g., polymyxin)
3. Inhibit protein synthesis (e.g., kanamycin, chloramphenicol)
4. Inhibit DNA or RNA synthesis (e.g., streptomycin)
A. Collagen is a structural protein that is
primarily located in the extracellular matrix.
B. Estrogen receptor is a nuclear receptor protein that can bind estrogen and
transduce signals into the cell nucleus to regulate gene expression. To enter
the cell nucleus, estrogen receptor requires a nuclear localization signal, so it
most likely contains an NLS.
E. Ubiquitination of protein lead
to degradation in proteosome
C. Kinesin belongs to a class of motor proteins. Kinesins move along
microtubule filaments and are powered by the hydrolysis of ATP.
D. Phosphofructokinase is a cytoplasmic enzyme involved in the glycolysis
pathway and mainly functions in the cytoplasm.
A signal peptide (sometimes referred to as signal sequence, targeting signal, localization
signal, localization sequence, transit peptide, leader sequence or leader peptide) is a
short peptide (usually 16-30 amino acids long) present at the N-terminus (or
occasionally nonclassically at the C-terminus or internally) of most newly synthesized
proteins that are destined toward the secretory pathway.
1. Applying a primary stain (crystal violet) to a heat-fixed
smear of a bacterial culture.
2. The addition of iodine, which binds to crystal violet and
traps it in the cell.
3. Rapid decolorization with ethanol or acetone.
4. Counterstaining with safranin.
Gram stain (Gram staining or Gram's method), is a method of
staining used to classify bacterial species into two large groups:
gram-positive bacteria and gram-negative bacteria.
Cellulose is synthesized by cellulose synthase complexes (CSCs) that are
assembled in the Golgi apparatus, transported to the cell membrane through
vesicles, and then secreted into the cell wall through exocytosis.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6447023/
C.
B.
D.
E.
Ca2+ does not bind to tropomyosin
Ca2+ binds to the troponin
complex, causing the myosinbinding sites on actin to
be exposed (Figure 50.29b)
An electrical synapse, also known as a gap junction, is a
mechanical link between two neurons that allows for the
conduction of electricity. Electrical synapses contain channels
that allow charges (ions) to flow from one cell to another
Two-component systems typically consist of a membranebound histidine kinase that senses a specific
environmental stimulus and a corresponding response
regulator that mediates the cellular response, mostly
through differential expression of target genes.
Motor Protein
Heme
The birth of cellulose occurs at the plasma membrane,
where a structure called the rosette terminal complex —
often called simply the rosette — synthesizes β-1,4 glucan
chains using UDP–glucose as substrate
Cell wall lignification 木质化 is a complex process
occurring exclusively in higher plants; its main function is
to strengthen the plant vascular body. This process
involves the deposition of ill-defined phenolic polymers,
the so-called lignins, on the extracellular polysaccharidic
matrix.
BBO
2020
真题来源：2020, 8.
Which of the following organelles is surrounded 下列哪种细胞器被双层膜包围？
by a double membrane?
A. Lysosome
B. Nucleus
C. Peroxisome
D. Smooth endoplasmic reticulum
A.溶酶体
B.核
C.过氧物酶体
光滑内质网
真题来源：2020, 13.
In which of the following would ribosomal
RNA be found?
1. Chloroplast
2. Lysosome
3. Mitochondrion
4. Nucleus
A. 1 and 3 only
B. 2 and 4 only
C. 1, 2 and 3 only
D. 1, 3 and 4 only
核糖体 RNA 存在于以下哪种物质中？
1.叶绿体
2.溶酶体
3.线粒体
4.细胞核
A.仅 1 和 3
B.仅 2 和 4
C.仅 1、2 和 3
D.只有 1、3 和 4
真题来源：2020, 14.
Which factor impedes the movement of water
molecules across a cell membrane?
哪个因素会阻碍水分子穿过细胞膜？
A. Water molecules and the phospholipid fatty acid tails
are both non-polar
B. Water molecules and the phospholipid fatty acid tails
are both polar
C. Water molecules are non-polar but the phospholipid
fatty acid tails are polar
D. Water molecules are polar but the phospholipid fatty
acid tails are non- polar
A.水分子和磷脂脂肪酸尾部都是非极性的
B.水分子和磷脂脂肪酸尾部都具有极性
C.水分子是非极性的，但磷脂脂肪酸尾部
是极性的
D.水分子是极性的，但磷脂脂肪酸尾部是
非极性的
真题来源：2020, 15.
Tannins are chemicals produced by plants to defend
themselves against herbivores, pathogens and UV radiation.
They are found in grapes and help wine age.
In 2013 a group of scientists discovered that tannins are
formed in separate organelles inside plant cells which they
termed tannosomes. Tannosomes originate in chloroplasts as
smaller vesicles and ultimately end up in the vacuole.
单宁酸是植物为抵御食草动物、病原体和紫外线辐
射而产生的化学物质。它们存在于葡萄中，有助于
葡萄酒的陈酿。
2013 年，一组科学家发现，单宁酸是
在植物细胞内形成的独立细胞器，他们称之为单宁
体。单体起源于叶绿体中的较小囊泡，最终进入液
泡。关于单宁体，下列哪些说法必须为真？
Which of the following statements must be true of
tannosomes?
A. Tannosomes are able to convert light energy to chemical
energy
B. Tannosomes are bound by a phospholipid bilayer
C. Tannosomes contain DNA and can replicate independently
of the cell
D. Tannosomes can only be present in green plant cells
A.丹宁体能够将光能转化为化学能
B.丹宁体由磷脂双分子层结合
C.丹宁体含有 DNA，可独立于细胞进行复制
D.单宁体只能存在于绿色植物细胞中
真题来源：2020, 16.
The coenzymes NAD and NADP are used in the processes of
respiration
and photosynthesis. They can exist in oxidised or reduced
forms. What is the most likely ratio of the oxidised : reduced
form in the
mitochondrial matrix and in the stroma of chloroplasts?
(A high ratio of oxidised : reduced indicates that most of the
coenzyme
is in its oxidised form).
辅酶 NAD 和 NADP 用于呼吸作用和光合作用。它
们可以以氧化或还原的形式存在。
线粒体基质和叶绿体基质中氧化型和还原型的比例
最有可能是多少？
(氧化：还原的比率高，说明大部分辅酶处于氧化状
态）。
真题来源：2020, 19.
Which of the following is responsible for the high resolution
of an
electron microscope?
A. Extremely thin sections
B. High magnification
C. The short wavelengths of the electron beam
D. Using heavy metal stains
以下哪项是电子显微镜高分辨率的原因？
A.极薄切片
B.高倍率
C.电子束的短波长
D.使用重金属染色剂
真题来源：2020, 21.
Which of these methods cannot be used to transport large
molecules across the cell surface membrane?
A. Active transport
B. Endocytosis
C. Facilitated diffusion
D. Osmosis
在这些方法中，哪一种 不能 用于跨细胞表面膜运
输大分子？
A.主动运输
B.内吞
C.促进传播
D.渗透
真题来源：2020,22.
The flow diagram shows some of the light dependent reaction
(LDR)
processes in photosynthesis.
For the LDR to continue, photosystem 2 (PS2) must gain
electrons.
Where do these electrons come from?
A. ATP production
B. Photolysis
C. Photosystem 1
D. Reduced NADP
流程图显示了光合作用中的一些光依赖反
应 (LDR) 过程。
为了让 LDR 继续，光系统 2 (PS2) 必须
获得电子。这些电子从何而来？
A.
B.
C.
D.
ATP 生产
光合作用
光系统 1
减少的 NADP
真题来源：2020,47.
Which of the following does not need to use transporter
proteins to cross cell membranes?
以下哪种物质不需要使用转运蛋白来穿过
细胞膜？
A. ATP
B. Glucose
C. mRNA
D. Proteins
E. Testosterone
A.ATP
B.葡萄糖
C.mRNA
D.蛋白质
E.睾酮
真题来源：2020,51.
Which pair of organelles has internal membranes?
A. Ribosomes and mitochondria
B. Mitochondria and chloroplasts
C. Nuclei and chloroplasts
D. Nuclei and ribosomes
哪对细胞器有内膜？
A.
B.
C.
D.
核糖体和线粒体
线粒体和叶绿体
细胞核和叶绿体
细胞核和核糖体
真题来源：2020,68.
You want to estimate the number of cells in a sample.
You take a portion of the sample, dilute it and add it to a cell
chamber
(haemocytometer) which contains squares of a known volume
and look at it
with a microscope.
What is true about the estimate you make?
A. It will be higher if you add more sample to the cell chamber
B. It will be more accurate if you count all of the cells which
overlap with the
borders of the squares you count
C. It will be more accurate if you count cells in more of the squares
D. It would be more accurate if the sample was diluted more
E. It would be more accurate if you use the small central squares to
count larger cells
您想估算样本中的细胞数。
您取一部分样本，稀释后将其添加到装有已知
体积正方形的细胞室（血细胞计数器）中，然
后用显微镜观察。
您所做的估算有哪些真实性？
A.
B.
C.
D.
E.
如果在样品室中添加更多的样品，数值会更高。
如果您计算的所有单元格都与您所计算的方格的
边界重叠，则会更加准确
如果对更多方格中的细胞进行计数，则会更加准确
如果样本稀释得更多，准确度会更高。
如果用中央的小方格来计算较大的单元格，会
更加准确
2021
真题来源：2021, S11, 22.
The way groups of organisms live depends on
fundamental aspects of their biology. For each of these
characteristics, state whether they belong to plants,
animals, fungi and/or bacteria.
Have cell walls. (1 mark)
A) Plants, animals, fungi
B) Plants, bacteria, fungi
C) Animals, fungi, bacteria
D) Plants, animals, bacteria
E) Plants, animals, bacteria, fungi
生物群落的生活方式取决于其生物学的基本方面。
对于每个特征,请说明它们属于植物、动物、真菌和
/或细菌。
有细胞壁。(1分)
A)植物、动物、真菌
B)植物、细菌、真菌
C)动物、真菌、细菌
D)植物、动物、细菌
E)植物、动物、细菌、真菌
真题来源：2021, S11, 23.
The way groups of organisms live depends on
fundamental aspects of their biology. For each of these
characteristics, state whether they belong to plants,
animals, fungi and/or bacteria.
生物群落的生活方式取决于其生物学的基本方面。
对于每个特征,请说明它们属于植物、动物、真菌和
/或细菌。
有线粒体。(1分)
Have mitochondria. (1 mark)
A) Plants, animals, fungi
B) Plants, bacteria, fungi
C) Animals, fungi, bacteria
D) Plants, animals, bacteria
E) Plants, animals, bacteria, fungi
A)植物、动物、真菌
B)植物、细菌、真菌
C)动物、真菌、细菌
D)植物、动物、细菌
E)植物、动物、细菌、真菌
真题来源：2021, S11, 25.
The way groups of organisms live depends on
fundamental aspects of their biology. For each of
these characteristics, state whether they belong to
plants, animals, fungi and/or bacteria.
生物群落的生活方式取决于其生物学的基本方面。
对于这些特征中的每一个,请说明它们属于植物、动
物、真菌和/或细菌。
大多数可以有性繁殖。(1分)
Most can reproduce sexually. (1 mark)
A) Plants, animals, fungi
B) Plants, bacteria, fungi
C) Animals, fungi, bacteria
D) Plants, animals, bacteria
E) Plants, animals, bacteria, fungi
A)植物、动物、真菌
B)植物、细菌、真菌
C)动物、真菌、细菌
D)植物、动物、细菌
E)植物、动物、细菌、真菌
2022
真题来源：2022, P2.
Lysosomes are membrane-bound organelles which contain
digestive enzymes. Which cell type would be best for studying
lysosomes?
溶酶体是含有消化酶的膜结构细胞器。
哪种细胞类型最适合研究溶酶体？
题目 2. 选择最合适的答案
Problem 2. Select the most appropriate answer
A) Fast-twitch muscle cell
B) Neuron
C) Bacterial cell
D) Phagocytic white blood cell
Human lysosome within cell
A) 快速肌肉细胞
B) 神经元
C) 细菌细胞
D) 吞噬性白细胞
人体细胞内的溶酶体
真题来源：2022, P3.
Which of the following are passive/facilitated (energetically
favourable) processes in cells?
题目3：以下哪些是细胞中的被动/促进（不消耗能量）
过程？
Problem 3. Choose as many as appropriate
选择所有适当的答案
A) The establishment of a concentration gradient
B) Osmosis
C) Diffusion
D) The hydrolysis of ATP
E) Synthesising a protein
F) Nucleotide polymerisation
A) 建立浓度梯度
B) 渗透作用
C) 扩散
D) ATP的水解
E) 合成蛋白质
F) 核苷酸聚合
真题来源：2022, P4.
Mitochondria have very crenated (creased) inner membranes, and the thylakoid membranes of chloroplasts are also highly
folded and stacked.
线粒体的内膜呈现锯齿状（高度褶皱），叶绿体的类囊体薄膜也紧密堆积并折叠。
Transmission electron microscope image credit Louisa Howard
透射电子显微镜下的图像 (图像来源：Louisa Howard)
Problem 4. Why are the membranes of mitochondria and chloroplasts folded?
题目 4：线粒体和叶绿体的膜为什么是折叠的？
1 mark
Choose ONE 单选
A. To maximise the amount of membrane for protons and electrons to diffuse through. 最大限度增加质子和电子扩散通过的膜层
数。
B. To increase the concentration gradient of protons. 增加质子的浓度梯度。
C. To maximise the amount membrane-bound of respiratory / photosynthetic proteins which can fit in the cell. 最大限度增加用于细
胞呼吸/光合作用的蛋白质的膜结合量。
D. To increase the amount of light absorbed by the membranes. 增加膜吸收的光线
E. To maximise the amount of protons / electrons which can be stored by the membranes. 最大限度增加膜存储的质子/电子数量
真题来源：2022, P30.
Two marks
Choose one. Single-choice
两分
选择一项。单选
Problem 30. In most organisms, in some cells, mitosis occurs
without cytokinesis. This may result in...
题目 30：在大多数生物体的某些细胞中，有丝分裂在
没有胞质分裂的情况下发生。这可能会导致......
A) cells with more than one nucleus.
B) cells that are unusually small.
C) cells lacking nuclei.
D) cell cycles lacking an S phase.
A) 细胞的细胞核不止一个
B) 细胞非常小
C) 细胞没有细胞核
D) 细胞周期缺少 S期
真题来源：2022, P31.
Two marks
Choose one. Single-choice
两分
选择一项。单选
Problem 31. What may happen if cytokinesis occurs without
mitosis?
A) Cells with more than one nucleus.
B) Cells lacking nuclei.
C) Cells that are unusually large.
题目 31：如果胞质分裂在没有有丝分裂的情况下发生，
会发生什么？
A) 细胞的细胞核不止一个
B) 细胞没有细胞核
C) 细胞体积异常大
真题来源：2022, P131.
A woman is suspected of having an E. coli infection. The hospital needs to work out how severe the infection is and which antibiotic to give the
patient.
一名妇女疑似感染大肠杆菌。医院需要判断出患者感染的严重程度以及给患者使用哪种抗生素。
● 2 mL of blood from the patient was diluted 98 mL of buffer solution. 将患者的 2 毫升血液稀释到 98 毫升缓冲溶液中。
● 1 mL of this solution was then diluted into 99 mL of buffer. 然后将 1 毫升该溶液稀释到 99 毫升缓冲液中。
● This was repeated twice more. 将以上过程重复两次。
● For each dilution, 1 mL and 0.1 mL of solution was plated on an agar plate. 每稀释一次，都将 1 毫升和 0.1 毫升溶液涂抹在琼脂平板上。
After 24h, the number of bacterial colonies (colony forming units; CFU) were counted. 24 小时后，计算菌落数（菌落形成单位；CFU）。
CFU counts are only reliable between 5 and 250 CFU. CFU 计数的结果仅在 5 到 250 CFU 之间是可靠的。
A dilution series of liquids, which are subsequently plated. 随后涂抹在琼脂平板上的一系列稀释溶液。
Problem 131. Which CFU count should doctors use to calculate the severity of this infection?
题目 131：医生应该使用哪种 CFU 计数来判断患者感染的严重程度？
1 mark
Choose ONE 单选
A. Too many to count 不计其数
B. 612
C. 87
D. 6
E. 1
真题来源：2022, P132.
Problem 132.
What is the number of CFU per mL of blood?
3 marks
Choose one
A. 612
B. 870
C. 6120000
D. 435000000
E. 4350000000
题目 132：每毫升血液的 CFU 数量是多少？
A. 612
B. 870
C. 6120000
D. 435000000
E. 4350000000
真题来源：2022, P133.
The doctors thought this infection was severe enough to need
antibiotics. However, many E. coli strains have
antibiotic resistance. Therefore, some of the patients E. coli was
streaked onto agar plates containing antibiotics,
as shown below.
Problem 133. Which antibiotic should the doctor prescribe?
1 mark
Choose ONE 单选
A. Ampicillin
B. Spectinomycin
C. Penicillin
D. Gentamicin
E. All of them
医生们认为患者感染非常严重，需要使用抗生素。然而，许多
大肠杆菌菌株具有抗生素耐药性。因此，部分患者的大肠杆菌
被接种到含有抗生素的琼脂平板上，如下图所示。
题目 133：医生应该开哪种抗生素？
1 mark
A. 氨苄西林
B. 大观霉素
C. 青霉素
D. 庆大霉素
E. 以上所有
真题来源：2022, P134.
Problem 134. What causes this patient's bacteria to be resistant to the antibiotics?
题目 134：什么会导致这位患者的大肠杆菌对抗生素产生耐药性？
1 mark
Choose ONE 单选
A. In response to the antibiotic, her E. coli evolved a resistance gene
为应对抗生素，患者的大肠杆菌产生了一个耐药基因
B. All E. coli are resistant to antibiotics by default
正常情况下，所有大肠杆菌都对抗生素有耐药性
C. Her E. coli already had antibiotic resistance genes in its genome
患者的大肠杆菌基因组中已经有抗生素抗性基因
真题来源：2022, P135.
Problem 135. What should the negative control plate contain?
1 mark
问题 135. 阴性对照板应包含什么?
1 分 选择一项 单选
Choose ONE 单选
A. A mix of all the antibiotics
B. E. coli which are resistant to all antibiotics
C. No antibiotic
D. Agar which does not have all the nutrients E. coli needs
E. None of the patient's E. coli
A. 所有抗生素的混合物
B. 对所有抗生素都有抗药性的大肠杆菌
C. 不含抗生素
D. 不含大肠杆菌所需的所有营养物质的琼脂
E. 患者的大肠杆菌都不含
2023
真题来源：2023, Paper 1, Q8, 1+2.
第 1 部分，共 7 个
Part 1 of 7
下面的逻辑谜题是根据**定义特征**和**共同特征**设计的。
The following logic puzzles are based on **defining
characteristics** and **shared traits** of branches of the tree of life. 生命树各分支的**定义特征**和**共有特征**。例如，脊椎动
For example, vertebrate animals share many characteristics (pairs of 物有许多共同特征
(例如，脊椎动物有许多共同特征（成对的附肢、脊索、背骨
appendages, spinal cords, digestive tract below backbone), some of 下面的消化道），其中有些可能是它们独有的，但它们是****
which may be unique to them, but they are *defined* by having a
的。
backbone divided into jointed vertebrae.
但它们的**定义是，它们的背骨被分成若干节脊椎骨。
Part 2 of 7
*Mitochondria are to Eukaryotes as X are to plants.* What is X?
1 mark
Choose ONE
a) Cell walls
b) Leaves
c) Plastids (e.g. chloroplasts)
d) Vacuoles
e) Nuclei
第二部分
*线粒体之于真核生物，就像 X 之于植物*。
1 分
选择一个
a) 细胞壁
b) 叶
c) 质体（如叶绿体）
d) 液泡
e) 细胞核
真题来源：2023, Paper 1, Q13, 1+2.
Part 1 of 10
Bacteria (*Bacillus subtilis*) were treated with a chemical
which changes their membrane properties when stimulated with
laser light. When pulsed with light, the membrane rapidly
depolarises (as seen with blue colouring in the video). The
membrane then rapidly repolarises. *B. subtilis* normally lives
in the soil and guts of mammals.
Part 2 of 10
How frequently was the light pulsed?
1 mark
Choose ONE
a) 1 minute
b) 5 minutes
c) 10 minutes
d) 20 minutes
e) 30 minutes
f) 60 minutes
第 1 部分（共 10 页）用一种化学物质处理细
菌（*枯草杆菌*），这种化学物质在激光的刺激
下会改变其膜的特性。当受到光脉冲时，膜迅速
去极化（如视频中的蓝色）。然后膜迅速再极化。
第 2 部分（共 10 页）光脉冲的频率是多少？
1 分
选择一个
a) 1 分钟
b) 5 分钟
c) 10 分钟
d) 20 分钟
e) 30 分钟
f) 60 分钟
真题来源：2023, Paper 1, Q13, 3+4.
Part 3 of 10
The scientists wanted to see which
channels were important for response to
light stimulation. They looked at two
mutant bacteria which had Gene A (Δa)
or Gene B (Δb) deleted.
Part 4 of 10
Which genes were required for
response to light?
1 mark
Choose as many as appropriate
a) a
b) b
第 3 部分，共 10 页科学家们想知
道哪些通道对光刺激的反应很重要。
他们研究了两种删除了基因 A（Δa）
或基因 B（Δb）的突变细菌。
第 4 部分（共 10 页）哪些基因对
光的反应是必需的？
a) a
b) b
真题来源：2023, Paper 1, Q13, 5.
Part 5 of 10
Roughly how long does it take for *Bacillus
subtilis* to divide?
3 marks
Choose ONE
a) 15 minutes
b) 30 minutes
c) 45 minutes
d) 60 minutes
e) 75 minutes
f) 90 minutes
第 5 部分（共 10 页）*枯草杆菌*
分裂大约需要多长时间？
3 分
请选择一个
a) 15 分钟
b) 30 分钟
c) 45 分钟
d) 60 分钟es
e) 75 分钟
f) 90 分钟
真题来源：2023, Paper 1, Q13, 6.
Part 6 of 10
This experiment was carried out at room
temperature (22°C). What effect would repeating
it at 37°C have?
1 mark
Choose ONE
a) Faster cell division
b) Slower cell division
c) No change on cell division
d) No cell division
第 6 部分，共 10 分该实验在室温
（22°C）下进行。1 分
选择一项
a) 细胞分裂加快
b) 细胞分裂减慢
c) 细胞分裂无变化
d) 细胞不分裂
真题来源：2023, Paper 1, Q13, 7.
Part 7 of 10
This experiment was carried out at room
temperature (22°C). What effect would repeating
it at 70°C have?
1 mark
Choose ONE
a) Faster cell division
b) Slower cell division
c) No change on cell division
d) No cell division
第 7 部分，共 10 页
本实验在室温（22°C）下进行，如果在70 °C
下重复该实验会如何？ 1 分选择一项
a) 细胞分裂加快
b) 细胞分裂减慢
c) 细胞分裂无变化
d) 细胞不分裂
真题来源：2023, Paper 1, Q13, 8.
Part 8 of 10
This experiment was carried out at room
temperature (22°C). What effect would repeating
it at 37°C have?
1 mark
Choose ONE
a) Faster repolarisation
b) Slower repolarisation
c) No change on polarisation
第 8 部分，共 10 页
本实验在室温（22°C）下进行。
1 分
选择一项
a) 再极化速度加快
b) 再极化速度减慢
c) 极化没有变化
真题来源：2023, Paper 1, Q13, 9.
Part 9 of 10
第 9 部分（共 10 页
Assume membrane polarisation in *B. subtilis* is controlled 假设枯草杆菌*的膜极化控制与人类神经元
similarly to human neurons.
类似。
1 mark
1 分
Choose ONE
选择一项
a) The light pulses cause sodium ion channels to briefly open a) 光脉冲导致钠离子通道短暂快速开放
quickly
b) 光脉冲导致钠离子通道短暂缓慢打开
b) The light pulses cause sodium ion channels to briefly open c) 光脉冲导致钠离子通道短暂关闭
slowly
d) 光脉冲导致钠/钾 ATP 酶开启
c) The light pulses cause sodium ion channels to briefly shut
d) The light pulses cause sodium/potassium ATPase to turn
on
真题来源：2023, Paper 1, Q13, 10.
Part 10 of 10
Assume membrane polarisation in *B. subtilis* is controlled
similarly to human neurons.
1 mark
Choose ONE
a) The light pulses cause potassium ion channels to briefly open
quickly
b) The light pulses cause potassium ion channels to briefly open
slowly
c) The light pulses cause potassium ion channels to briefly shut
d) The light pulses cause sodium/potassium ATPase to turn *off*
第 10 部分（共 10 分）假设枯草杆菌*的
膜极化控制与人类神经元类似。
1 分
选择一项
a) 光脉冲导致钾离子通道短暂快速开放
b) 光脉冲导致钾离子通道短暂缓慢开放
c) 光脉冲导致钾离子通道短暂关闭
d) 光脉冲导致钠/钾ATP酶关闭**。
2024
真题来源：2024, Paper 1, Q10, 1
In 2024, scientists reported finding fossilised microorganisms which 2024 年，科学家报告说发现了微生物化石，其中含有折叠的内
contained folded internal membranes which looked like thylakoids. 膜，看起来就像葡萄体。 这些化石距今已有 17.5 亿年的历史
At 1.75 billion years old, these are the oldest fossilised thylakoids.
，是最古老的叶绿体化石。
T or F?
1. The organism certainly had chloroplasts. (False)
2. The organism certainly had mitochondria. (False)
3. Organisms like this could be responsible for the 'oxygen
catastrophe' (the accumulation of free O2​ in the atmosphere). (True)
该生物肯定有叶绿体。 (错）
该生物肯定有线粒体。 (错）
这种生物可能是 "氧气灾难"（大气中游离 O2 的积累）的罪魁
祸首。 (对)
真题来源：2024, Paper 1, Q10, 2
Why are key photosynthetic reactions carried out within/on
membranes?
T or F?
1. To maximise the surface area for the reaction. (True)
2. To maximise the amount of enzymes and pigments which can fit in
the cell. (False)
3. So potential gradients can be established to power other reactions.
(True)
4. To minimise the distance light and substrates must travel through
the cell. (False)
5. Because the substrates are hydrophobic. (False)
为什么关键的光合作用反应是在膜内/膜上进行的？
使反应的表面积最大化。 (对）
使细胞内可容纳的酶和色素数量最大化。 (假）
以便建立电位梯度，为其他反应提供动力。 (对）
使光和底物通过细胞的距离最小。 (假）
真题来源：2024, Paper 1, Q10, 3
T or F?
1. In plants, glucose moves into the chloroplast, where it enters the
citric acid (Krebs) cycle. (False)
2. Plant mitochondria produce ATP that can be used to drive essential
cell reactions. (True)
3. Plant chloroplasts carry out biosynthesis reactions and assimilate
inorganic molecules. (True)
4. Mitochondria can produce ATP only in the presence of oxygen.
(True)
T or F
在植物体内，葡萄糖进入叶绿体，在那里进入柠檬酸（克雷布斯
）循环。 (假）
植物线粒体产生的 ATP 可用于驱动细胞的基本反应。 (真）
植物叶绿体进行生物合成反应并吸收无机分子。 (真）
线粒体只有在有氧的情况下才能产生 ATP。(真
真题来源：2024, Q4, 1
Many organisms alter their physiology to suit the environment.
Iron is an essential nutrient but bio-available iron is scarce.
Pseudomonas aeruginosa is a bacteria which can survive in both
low- and high-iron environments. It can infect humans, but also live
outside."
The liver produces an iron chelating protein called transferrin.
Transferrin keeps the concentration of free iron in the blood very
low.
P. aeruginosa can create two siderophores. Siderophores are iron
chelators which are released into the environment where they can
bind iron, diffuse back towards the bacterium and be reabsorbed."
• Pyoverdine has a very low Kd (dissociation constant) and is
'expensive' to make.
• Pyochelin has a high Kd and is 'cheap' to make.
1. When infecting humans, P. aeruginosa will tend to make more of
both siderophores. (False)
2. In a high-iron environment, a mutant P. aeruginosa without
pyoverdine may be slightly fitter than wild-type. (True)
3. Pyoverdine from pathogenic P. aeruginosa has a lower Kd than
transferrin. (True)
4. P. aeruginosa receive more benefit from siderophores when they
are surrounded by other P. aeruginosa bacteria which are also
producing siderophores. (True)
5. The production of siderophores is likely to be controlled by both
iron availability and quorum sensing. (True)
T or F?
许多生物会改变其生理机能以适应环境。 铁是一种必需的营养物质，但生
物可利用的铁却很少。 铜绿假单胞菌是一种既能在低铁环境中生存，也能
在高铁环境中生存的细菌。 它可以感染人类，但也可以在户外生存"。 肝
脏会产生一种叫做转铁蛋白的铁螯合蛋白。 转铁蛋白能使血液中游离铁的
浓度保持在很低的水平。 铜绿假单胞菌能产生两种嗜苷酸盐。 嗜苷铁蛋白
是一种铁螯合剂，可释放到环境中与铁结合，扩散回细菌并被重新吸收。
• Pyoverdine 的 Kd（解离常数）非常低，制造成本'昂贵'。
• Pyochelin 的 Kd 值很高，制造起来很'便宜'。
1. 当感染人类时，铜绿假单胞菌倾向于制造更多的嗜苷酸盐。 (假
2. 在高铁环境中，不含吡咯韦啶的突变型铜绿假单胞菌可能比野生型稍
好。 (真）
3. 致病铜绿假单胞菌的吡咯韦啶的 Kd 值比转铁蛋白低。 (正确）
4. 当铜绿假单胞菌周围有其他铜绿假单胞菌时，铜绿假单胞菌能从嗜苷
酸盐中获得更多益处，因为其他铜绿假单胞菌也在生产嗜苷酸盐。
(正确）
5. 嗜苷酸的产生可能受铁的可用性和法定量感应的控制。 正确
真题来源：2024, Paper 2, Q4, 2
For the following metabolic processes, decide whether iron is an
essential nutrient.
对于下列代谢过程，请判断铁是否是必需营养素。