Mock Exam Set 1 - Paper 1

The giant algae Acetabularia can be a model organism for studying the biology of a plant cell. Which characteristics of Acetabularia make it a good model organism?

• A.$\hspace{1em}$ Both, Acetabularia cells and plant cells, do not have a cell wall.

• B.$\hspace{1em}$ Acetabularia is composed of one large cell.

• C.$\hspace{1em}$ Acetabularia is composed of many large cells.

• D.$\hspace{1em}$ Acetabularia contains a pigment which makes its structures easily visualised.

The electron micrograph shows a sarcomere, the smallest functional unit of striated muscle tissue. What is the actual length between the two Z lines?

[Source: Adapted from Loison, O., Weitkunat , M., Kaya-Çopur , A., Nascimento Alves, C., Matzat , T., & Spletter , M. L. (2018). Category: sarcomeres. Wikimedia Commons. Retrieved March 5, 2023, from https://commons.wikimedia.org/wiki/Category Copyright under CC BY 3.0][Ruler tool, cm]

• A.$\hspace{1em}$ 10 µm

• B.$\hspace{1em}$ 1 mm

• C.$\hspace{1em}$ 1 cm

• D.$\hspace{1em}$ 1 µm

Mesophyll cells are found in plants. Plant cells have unique characteristics that distinguish them from any other cell type.

[Source: Adapted from Zhang, N., Zhang, L., Zhao, L., Ren, Y., Cui, D., Chen, J., ... & Chen, F. (2017). iTRAQ and virus-induced gene silencing revealed three proteins involved in the cold response in bread wheat. Scientific reports, 7(1), 1-16.Retrieved March 27, 2022. From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548720/. Copyright under CC by 4.0]

In the micrograph above, one of the cell parts is labelled X. What is the name of this structure?

• A.$\hspace{1em}$ Chloroplast

• B.$\hspace{1em}$ Central vacuole

• C.$\hspace{1em}$ Cell wall

• D.$\hspace{1em}$ Starch granule

The important properties of animal cell membranes are fluidity and permeability. Which molecule is responsible for ensuring the membrane’s fluidity?

• A.$\hspace{1em}$ Cholesterol

• B.$\hspace{1em}$ Integral Membrane Proteins

• C.$\hspace{1em}$ Glycolipids

• D.$\hspace{1em}$ Peripheral Membrane Proteins

When is the concentration of cyclin E the highest during the cell cycle ?

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Biomolecules have diverse forms and structures. Which of the following statements is false?

• A.$\hspace{1em}$ Deoxyribose can be differentiated from ribose because of the absence of the hydroxyl (-OH) group on the 2’ carbon.

• B.$\hspace{1em}$ Amino acids consist of an amino group, an acidic carboxyl group and an organic R group.

• C.$\hspace{1em}$ Phospholipids are lipid molecules with a hydrophobic “head” and two hydrophilic “tails.”

• D.$\hspace{1em}$ Glucose is an example of a monosaccharide.

Which of the following statements about lipids is true?

• A.$\hspace{1em}$ It is advisable to add trans fats to one’s diet.

• B.$\hspace{1em}$ There is a carbon-carbon triple bond in monounsaturated fats.

• C.$\hspace{1em}$ Polyunsaturated fats are made up of carbon-carbon single bonds to keep them in a liquid state.

• D.$\hspace{1em}$ Saturated fats are made up of carbon-carbon single bonds.

The most abundant catalytic protein in a vascular plant is found in the leaves. What is the name of this protein?

• A.$\hspace{1em}$ Insulin

• B.$\hspace{1em}$ Rubisco

• C.$\hspace{1em}$ Rhodopsin

• D.$\hspace{1em}$ Collagen

What is the substrate for the enzyme lactase?

• A.$\hspace{1em}$ Glucose

• B.$\hspace{1em}$ Galactose

• C.$\hspace{1em}$ Lactose

• D.$\hspace{1em}$ Fructose

A strand of nucleotides reads CCUAGAGCUUACCG. Which type of pentose sugar could be found in the nucleotides in this strand?

• A.$\hspace{1em}$ Deoxyribose only

• B.$\hspace{1em}$ Ribose only

• C.$\hspace{1em}$ Both deoxyribose and ribose

• D.$\hspace{1em}$ Neither deoxyribose nor ribose

The table gives the genetic code.

[Source: CNX OpenStax. (2016, November 11). File: OSC Microbio 11 04 GenCode.jpg. Wikimedia Commons. Retrieved January 4, 2023, from https://commons.wikimedia.org/wiki/File: OSC_Microbio_11_04_GenCode.jpg. Copyright under CC-BY 4.0]

Which polypeptide is produced by the mRNA sequence AUG GCU AAA UAG CGA?

• A.$\hspace{1em}$ Met-Ala-Lys

• B.$\hspace{1em}$ Met-Ala-Lys-Tyr-Arg

• C.$\hspace{1em}$ Met-Arg-Asn

• D.$\hspace{1em}$ Met-Arg-Asn-Cys-Arg

The graph below shows the changes in the levels of lactate on the skin of athletes during pre-training (rest), training, and recovery.

[Source: Adapted from Ohkuwa, T., Tsukamoto, K., Yamai, K., Itoh, H., Yamazaki, Y., & Tsuda, T. (2009). The relationship between exercise intensity and lactate concentration on the skin surface. International Journal of Biomedical Science: IJBS, 5(1), 23. Retrieved March 27, 2022. From https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614747/ Copyright © Tetsuo Ohkuwa et al. Licensee Master Publishing Group. Copyright under CC BY]

Based on the graph, which is true?

• A.$\hspace{1em}$ There was no lactate during pre-training because there was no cellular respiration.

• B.$\hspace{1em}$ As exercise intensity increased, anaerobic respiration increased.

• C.$\hspace{1em}$ During periods of exercise, lactate levels remained constant.

• D.$\hspace{1em}$ During the recovery periods, aerobic and anaerobic respiration continuously increased.

The image shows an abnormal human karyotype.

[Source: Adapted from Wessex Reg. Genetics Centre. (n.d.) Down syndrome human karyotype 47,XY. Retrieved March 29, 2022, from https://wellcomecollection.org/works/wmcdanw6. Copyright under CC BY 4.0]

What is the abnormality in this karyotype and its cause?

At the end of which phase of meiosis I does crossing over occur, and what is the outcome of crossing over?

A biological male with haemophilia and a biological female without haemophilia have a daughter without haemophilia. What are the possible genotypes of the daughter?

• I.	XHXH
  II.	XHXh
  III.	XhXh

• A.$\hspace{1em}$ I only

• B.$\hspace{1em}$ II only

• C.$\hspace{1em}$ II and III only

• D.$\hspace{1em}$ I, II and III

The diagram shows a DNA profile of a child and the profiles of three potential pairs of parents. Which pair(s) could be the actual parents of the child?

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• A.$\hspace{1em}$ Parents X only

• B.$\hspace{1em}$ Parents Y only

• C.$\hspace{1em}$ Parents Y and Z only

• D.$\hspace{1em}$ Parents X and Z only

Chytrids are unicellular organisms that feed on pollen through extracellular secretion of digestive enzymes and absorption of the breakdown products. Which statement describes the nutritional mode of this organism?

• A.$\hspace{1em}$ Autotrophic producer

• B.$\hspace{1em}$ Autotrophic consumer

• C.$\hspace{1em}$ Heterotrophic detritivore

• D.$\hspace{1em}$ Heterotrophic saprotroph

The illustration shows a rice cultivation system that eliminates the need for fertilizers, herbicides and pesticides by raising ducks in rice paddies. Additionally, Azolla, an aquatic floating fern, is grown in these fields because they harbour blue-green algae that fixes N$_2$. This system produces duck, fish and rice for human consumption.

[© Revision Village 2022. Created with BioRender.com]

What would be a possible food chain for the rice cultivation system shown in the image?

• A. $\hspace{1em}$ algae $\rightarrow$ fish $\rightarrow$ duck $\rightarrow$ human

• B. $\hspace{1em}$ algae $\leftarrow$ fish $\leftarrow$ duck $\leftarrow$ human

• C. $\hspace{1em}$ insects $\rightarrow$ algae $\rightarrow$ duck $\rightarrow$ human

• D. $\hspace{1em}$ insects $\leftarrow$ algae $\leftarrow$ duck $\leftarrow$ human

The diagram illustrates the carbon cycle in a swamp. What is represented by the letters?

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Which characteristics of carbon dioxide make it a greenhouse gas of concern?

• A.$\hspace{1em}$ Absorbs long wave radiation and has a significant concentration in the atmosphere.

• B.$\hspace{1em}$ Emits shortwave radiation and has a significant concentration in the atmosphere.

• C.$\hspace{1em}$ Absorbs shortwave radiation and has a high stability.

• D.$\hspace{1em}$ Blocks infrared radiation and has a high stability.

The peppered moth (Biston betularia) is often used as an example when discussing industrial melanism.

[Source: Sale, B.(2010, July 8). File:(1931) Peppered Moth (Biston betularia) - f.carbonaria (4777708667).jpg. Wikimedia Commons. Retrieved October 30, 2022, from https:// commons.wikimedia.org/wiki/File:(1931)Peppered_Moth(Biston_betularia)_-f.carbonaria(4777708667).jpg. CC-BY-2.0.]

Which of the following is responsible for the increase in the proportion of the melanic form during the industrial revolution?

• I. $\hspace{1em}$ Increased mutation rate
• II. $\hspace{.7em}$ Natural selection
• III. $\hspace{.5em}$ Sexual selection

• A. $\hspace{1em}$ I only

• B. $\hspace{1em}$ II only

• C. $\hspace{1em}$ I and II only

• D.$\hspace{1em}$ I, II and III

A population of plants with no resistance to herbivores may develop into a population of plants that secrete a compound toxic to herbivores. How could this change occur?

• A.$\hspace{1em}$ The gene for the toxic compound was inherited from an ancestor of the plant population.

• B.$\hspace{1em}$ A mutation during DNA replication, prior to meiosis, resulted in a DNA sequence that codes for the compound.

• C.$\hspace{1em}$ The enzyme needed to produce the compound was transferred by a plant from another population.

• D.$\hspace{1em}$ Individuals in the plant population mutated in response to the pressure from herbivores.

The phylogenetic tree below shows relationships among species in four phyla of land plants.

[Source: Adapted from Sousa, F., Civáň, P., Foster, P.G., and J. Cymon. (July, 2020). The Chloroplast Land Plant Phylogeny: Analyses Employing Better-Fitting Tree- and Site-Heterogeneous Composition Models. Front. Plant Sci. 11:1062. Retrieved January 4, 2023 from https://www.researchgate.net/publication/343263276_The_Chloroplast_Land_Plant_Phylogeny_Analyses_Employing_Better-Fitting_Tree-and_Site-_Heterogeneous_Composition_Models. Copyright under CC BY 4.0]

The divisions of land plants have important differences. Which of these phyla produce seeds?

• A.$\hspace{1em}$ Angiospermophyta only

• B.$\hspace{1em}$ Coniferophyta and angiospermophyta

• C.$\hspace{1em}$ Bryophyta only

• D.$\hspace{1em}$ Bryophyta and filicinophyta

Early cladograms were constructed by comparing structures of organisms. The cladogram on the left is based on structure and the cladogram on the right is based on comparing the DNA sequence of a particular gene.

[Source: Left: Adapted from Milinkovitch, M., Thewissen, J. (1997). Even-toed fingerprints on whale ancestry. Nature 388, (622–623). Retrieved January 4, 2023, from https://doi.org/10.1038/41650. Copyright under open access; Right: Adapted from Masato Nikaido, Alejandro P. Rooney, Norihiro Okada. (1999, August 31). Phylogenetic relationships among cetartiodactyls based on insertions of short and long interpersed elements: Hippopotamuses are the closest extant relatives of whales. Proceedings of the National Academy of Sciences. Retrieved January 4, 2023, from https://www.pnas.org/doi/10.1073/pnas.96.18.10261. Copyright-free.]

What is the reason that the cladogram based on the DNA sequences is a more reliable representation of the sequence of divergence among clades than the cladogram based on structures?

• A.$\hspace{1em}$ Structures are not inherited when species diverge.

• B.$\hspace{1em}$ DNA does not change over time while structures can change over time.

• C.$\hspace{1em}$ Similar structures can be coded for by different genes in genetically distant organisms.

• D.$\hspace{1em}$ There are many different structures that are coded for by the same DNA sequence.

Which structure in humans produces bile for the emulsification of lipids?

• A.$\hspace{1em}$ Gall bladder

• B.$\hspace{1em}$ Small intestine

• C.$\hspace{1em}$ Liver

• D.$\hspace{1em}$ Pancreas

What helps prevent the backflow of blood in a vein?

• A.$\hspace{1em}$ Relaxation of skeletal muscles

• B.$\hspace{1em}$ Venous valves

• C.$\hspace{1em}$ Relaxation of the heart

• D.$\hspace{1em}$ Thin vessel walls

Which of the following is associated with non-specific immunity?

• A. $\hspace{1em}$ Lymphocytes

• B. $\hspace{1em}$ Antibodies

• C. $\hspace{1em}$ Memory cells

• D. $\hspace{1em}$ Mucus

The image below compares the mortality rate for smokers and non-smokers over the age of 40.

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Based on the graph above, which statement is correct?

• A.$\hspace{1em}$ Smoking is the cause of early death.

• B.$\hspace{1em}$ More smokers survive at the age of 90.

• C.$\hspace{1em}$ A smoker and a non-smoker have the same chances of survival at the age of 70.

• D.$\hspace{1em}$ After 60 years old, more non-smokers survive compared to smokers.

Some acetylcholine released by a motor neuron at the neuromuscular junction stimulates muscle contraction, while the remainder is rapidly removed from the synapse. Which processes are required for this to happen?

Which hormone is secreted by cells in adipose tissue and acts on the hypothalamus to inhibit appetite?

• A.$\hspace{1em}$ Melatonin

• B.$\hspace{1em}$ Leptin

• C.$\hspace{1em}$ LH

• D.$\hspace{1em}$ Glucagon