Biology and Biotechnology: Second-round sample tasks for the Open Doors undergraduate track

You will be asked to complete 35 tasks, including:

19 entry-level tasks, each correct answer worth 1 point;
13 intermediate-level tasks, each correctly answered task worth 3-4 points;
3 advanced tasks (constructed response), each correctly completed task valued at 12–13 points.

Evaluation criteria and standard answers are provided for the advanced tasks requiring constructed responses.

Biology

Which plant division is defined by reproduction through spores and the lack of a root system? a) Gymnosperms
b) Angiosperms
c) Mosses
d) Ferns
e) Brown algae
Entry level (1 point)

The excretory organs of the earthworm are: a) Pelvic kidneys
b) Protonephridia
c) Metanephridia
d) Coxal glands
e) Malpighian vessels
Entry level (1 point)

Aldosterone is produced by the gland: a) Hypothalamus
b) Pituitary
c) Adrenal
d) Renal
e) Pancreas
Entry level (1 point)

Haploid structures in gymnosperms are: a) Female cone
b) Pollen
c) Sperm
d) Male cone
e) Seed germ
Intermediate level (4 points)

The following have a closed circulatory system: a) Gastropod
b) Ringed worm
c) Fish
d) Fly
e) Snake
Intermediate level (4 points)

Virology

RNA viruses include: a) Variola virus
b) Varicella zoster virus
c) Human papillomavirus
d) Human herpes simplex virus
e) Yellow fever virus
Entry level (1 point)

The first to use vaccination against viral infection: a) E. Jenner
b) L. Pasteur
c) A. Flemming
d) R. Koch
e) I. Mechnikov
Entry level (1 point)

Viral diseases transmitted through blood include: a) Hepatitis A
b) Hepatitis B
c) Hepatitis C
d) Dysentery
e) Typhoid fever
Intermediate level (3 points)

The influenza virus is characterized by the presence of: a) DNA
b) RNA
c) Circular molecule
d) Linear single-chain (+)
e) Linear single-stranded (-)
Intermediate level (3 points)

Genetics and Heredity

What does crossing over refer to? a) The process of packaging chromosomes
b) The transfer of a chromosome segment to a non-homologous chromosome
c) The exchange of segments between homologous chromosomes during conjugation
d) The rotation of a chromosome segment by 180°
e) The loss of a segment from a chromosome
Entry level (1 point)

How many different types of gametes can an organism with the genotype aaBbCcDDee produce? a) 2
b) 4
c) 5
d) 8
e) 32
Entry level (1 point)

What might be the blood types of two children in a family where the mother is type I (0) and the father is type IV (AB)? a) I(0) and IV(AB)
b) I(0) and II(A)
c) I(0) and III(B)
d) II(A) and III(B)
e) II(A) and IV(AB)
Entry level (1 point)

Polyploidy is very common among cultivated plants. Let the allele A- be responsible for the absence of bitter substance in fruits, and the recessive allele a – for its presence. Two polyploids are crossed: ♂ AAaa × ♀AAaaaa. Check the correct statements a) Ratio among gametes of the paternal plant: 1AA: 2Aa:1aa
b) Ratio among gametes of the mother plant: 1AAa: 3Aaa: 1aaa
c) Chance of getting a bitter fruit offspring: 1/32
d) The offspring of this cross are likely to be sterile
e) All fruits produced as a result of crossing will not be bitter
Intermediate level (3 points)

The dominant allele of the R gene is responsible for the red color of corn grains, and the recessive r for yellow. The e allele leads to an increased amount of starch, while E is responsible for reduced starch content. Pollen is transferred from a homozygous line with red grains and high starch content (1) to the pistils of a homozygous line with yellow grains and low starch content (2). In the next generation, F1 hybrids are crossed with each other. Answer the following:

Crossing scheme (Parents, Gametes, Offspring):
Parents: ♂ RRee (red, high starch) × ♀ rrEE (yellow, low starch)
Gametes: Re, rE
Offspring (F1): RrEe (red, low starch)
Genotypes and color of F1 grains:
F1 grains will have the genotype RrEe, and their color will be red.
Gametes of F1 hybrids:
The possible gametes produced by F1 hybrids are: RE, Re, rE, re.
Genotypes and color of F2 grains:
In F2, grains can have the genotype RrEe, and the color will be red.

Advanced level (13 points)

Microbiology

Storage polysaccharides in bacteria are used as: a) Nitrogen source
b) Carbon source
c) Source of phosphorus
d) Sulfur source
e) Oxygen source
Entry level (1 point)

Microorganisms growing in the temperature range from 40 to 90°C and above belong to the group: a) Mesophiles
b) Thermotolerants
c) Thermophiles
d) Psychrophiles
e) Extremophiles
Entry level (1 point)

What groups of microorganisms are the main producers of antibiotics? a) Seaweed
b) Spore-forming bacteria
c) Actinomycetes
d) Molds
e) Protozoa
Intermediate level (3 points)

An experiment was designed at the research institute to assess the effect of a biological product based on microorganisms on wheat yield.

Experimental Data:

Sample no.	Repetition	Control		Experience
		MPA environment	Czapek + Streptomycin	MPA environment	Czapek + Streptomycin
1	1	27	23	55	34
	2	32	24	57	21
	3	34	27	60	37
2	1	43	32	61	43
	2	45	30	63	45
	3	47	36	68	42
3	1	23	31	70	26
	2	22	29	67	32
	3	20	27	64	24

Questions:

What microorganisms were taken into account in this experiment?

Heterotrophic (ammonifying) bacteria on MPA medium and soil fungi on Czapek medium with the addition of streptomycin.

What is the significance of adding streptomycin to Czapek's medium?

Streptomycin is a broad-spectrum antibiotic that inhibits the growth of bacteria without interfering with the growth of fungi.

What is the average number of each group of microorganisms present in 1 g of soil in the control and experiment?

The average number of microorganisms in the control and experiment can be calculated from the provided data, considering soil moisture adjustments. For instance, using the given data, the average calculated number for control soil is approximately 7294118 CFU/g when adjusted for soil moisture.

Did the biological product affect the number of microorganisms in the soil during this experiment? Did it affect all studied groups of microorganisms?

Yes, the biological product increased the number of microorganisms in the soil. It specifically affected the heterotrophic bacteria and soil fungi, as indicated by the higher counts in the experimental plots compared to the control plots.

How much of the drug should be used, provided that the manufacturer claims to contain at least 10^9 CFU/ml in the supplied drug?

According to the calculations, 2.5 liters of the drug should be used to meet the requirement of at least 10,000 CFU/cm² on the experimental field.

Advanced level (12 points)

Cytology

Plastids and mitochondria are similar in that they contain: a) Centrioles
b) Vacuoles
c) Electron transport chain in the membrane
d) Smooth endoplasmic reticulum
e) Golgi complex
Entry level (1 point)

If a fluorescent dye binds to the protein tubulin, which of the structures in the cell will be most clearly visible under a light microscope? a) Core
b) Mitochondria
c) Centriole or spindle
d) Vacuole
e) Nucleolus
Entry level (1 point)

Escherichia coli is characterized by: a) Gram - staining
b) Absence of pili and flagella
c) Lack of spore formation
d) Inability to grow under aerobic conditions
e) One membrane within the cell wall
Intermediate level (3 points)

What processes are characteristic of prophase 1 of meiosis? a) Divergence of monochromatid chromosomes
b) Shortening the spindle filaments
c) Conjugation of homologous chromosomes
d) Chromatin compaction
e) Cell septum formation
Intermediate level (3 points)

Ecology

The genus Nepenthes comprises carnivorous plants that have evolved modified leaves designed to trap a variety of insects. These insects are then digested and absorbed by the plants. This adaptation developed with the goal of… a) Obtaining energy
b) Obtaining organic carbon
c) Obtaining organic reducing agents
d) Obtaining water
e) Obtaining phosphorus and nitrogen
Entry level (1 point)

Select parasites whose intermediate host can be human: a) Bull tapeworm
b) Cat fluke
c) Echinococcus
d) Schistosoma
e) Pinworm
Entry level (1 point)

It is understood that energy is lost at each transition to the next trophic level. Please select the accurate statements: a) 90% of the energy goes to each next level
b) When moving to the next level, about 90% of energy is lost
c) This statement applies only to forest communities
d) The biomass of producers in the ecosystem will be equal to the biomass of consumers of the 1st order
e) In an ecosystem, the biomass of 1st consumers will be less than that of producers
Intermediate level (3 points)

Examples of mutualism include interactions: a) Shark and sticky fish
b) Sea anemones and hermit crab
c) Man and cockroach
d) Penguin and polar bear
e) Phycobiont and mycobiont of lichen
Intermediate level (3 points)

Biochemistry and Molecular Biology

At a substrate concentration of 3 Km (Michaelis constant), what is the rate of the enzyme reaction? a) 33% max speed
b) 66% maximum speed
c) 75% maximum speed
d) 90% maximum speed
e) 133% maximum speed
Entry level (1 point)

The tertiary structure of a protein is: a) α-helix held together by hydrogen bonds
b) Sequence of amino acid residues in a polypeptide chain
c) Mutual arrangement of several protein chains
d) Spatial configuration of an α-helix formed by covalent polar, nonpolar, and ionic bonds
e) β-sheets
Entry level (1 point)

Analyze the picture and choose the correct statements:

a) Contains conjugated aliphatic double bonds in the hydrocarbon skeleton
b) Contains aromatic structures
c) Synthesized from hexoses
d) Is a good reducing agent
e) Contains centers of optical isomerism
Intermediate level (4 points)

Calculation of restriction enzyme sites and DNA diameter

Restriction enzymes, also known as restriction endonucleases, are a class of enzymes that facilitate the hydrolysis of phosphodiester bonds within nucleic acid molecules. Today, these enzymes are essential tools for molecular biologists, enabling them to map genomes, construct vectors for bacterial transformation, produce proteins in vitro, and perform various other applications.

1) The average size of the bacterial genome of Escherichia coli is 6.72 Mb (6.72 × 10⁶ bp). It is understood that the length per nucleotide pair is 0.34 nanometers. Calculate the diameter of circular bacterial DNA in E. coli in mm, taking the approximate value π = 3.14. Give the answer in mm, rounded to two decimal places.

    To calculate the diameter of circular bacterial DNA:
    - Length of nucleotide chain = 6.72 × 10^6 bp × 0.34 nm/bp = 2.29 × 10^6 nm = 2.29 mm
    - Diameter = Circumference / π = 2.29 mm / 3.14 = 0.73 mm (rounded to two decimal places)

2) Let the AAGCTT restriction site be known for restriction enzyme A, and the AGCT restriction site for restriction enzyme B. Calculate how many restriction sites can be expected for restriction enzymes A and B, assuming a GC composition of 60%. Answer round to whole numbers.

    GC composition - 60%, thus:
    - p(G) = p(C) = 0.3
    - p(A) = p(T) = 0.2
    
    Number of restriction enzyme A sites:
    - (0.2)^5 × (0.3)^1 × 6.72 × 10^6 = 968 (rounded to whole numbers)
    
    Number of restriction enzyme B sites:
    - (0.2)^2 × (0.3)^2 × 6.72 × 10^6 = 24,192 (rounded to whole numbers)

Answer:

1. 0.72 mm
2. 968
3. 24,192

Evaluation Criteria:

Criterion 1: The correct answer to one question is provided. Length (3 points) and diameter (3 points) – total of 6 points.
Criterion 2: The number of restriction enzyme A sites is calculated – 3 points.
Criterion 3: The number of restriction enzyme B sites is calculated – 3 points.

Biotechnology and Applied Microbiology

As a selective marker indicating the presence of the vector in the genome, the following is introduced into the construct: a) Antibiotic resistance gene
b) Inducible transcription promoter
c) Origin of replication
d) mRNA polyadenylation signal
e) Polylinker
Entry level (1 point)

Identify the polymerase chain reaction (PCR) component responsible for synthesizing new nucleotide chains: a) Magnesium salts
b) Polymerase
c) Deoxynucleoside triphosphates
d) Buffer
e) DNA matrix
Entry level (1 point)

The lactose operon of a prokaryotic cell includes: a) Cistrons
b) Promoter
c) Terminator
d) Enhancer
e) Silencer
Intermediate level (4 points)

Shuttle plasmid vectors used for protein expression must contain: a) Origins of replication
b) Recombination sites
c) Polylinker
d) Marker genes
e) Promoter
Intermediate level (4 points)

Resource => Demo version

Program of Subject Area