Home / 2019 May Biology paper 1 TZ2 HL-Concepts Questions and Answers

2019 May Biology paper 1 TZ2 HL-Concepts Questions and Answers

  1. Given a magnification of 2000x in the micrograph, what is the maximum diameter of the nucleus in the cell labeled X?

     

    1. 10 μm

    2. 10 nm

    3. 20 μm

    4. 20 nm

      Ans: A

 

2. What accounts for the observed appearance of the cell in the micrograph?

    1. The cell is dying.

    2. The DNA is replicating.

    3. The cell is in metaphase.

    4. The cell is in telophase.

Ans: C

3. Which processes are implicated in the development of cancer?

  1. Mutations occur in oncogenes.

  2. Oncogenes prevent cancer.

  3. Oncogenes affect cell cycle regulatory proteins.

    1. I and II only

    2. I and III only

    3. II and III only

    4. I, II and III

      Ans: B

 

4. What is the explanation for the concentrations of potassium and sodium ions inside and outside human cells?

 

Concentration of ions / 10–3  mol dm–3

Ions

Intracellular

Extracellular

Potassium ions

135

4

Sodium ions

10

145

 

    1. Potassium ions enter through diffusion, while sodium ions exit through diffusion.

    2.  

      Sodium ions enter through diffusion, while potassium ions exit through diffusion.

    3.  

      Active transport mechanisms move sodium ions into the cell and potassium ions out.

    4.  

      Active transport mechanisms pump sodium ions out and potassium ions into the cell.

      Ans: D

5. In what context do hydrogen bonds form?

    1. Between the slight negative charge of hydrogen and slight positive charge of oxygen within a water molecule

    2. Between the slight positive charge of hydrogen and slight negative charge of oxygen within a water molecule

    3. Between the slight positive charge of hydrogen and slight negative charge of oxygen in distinct water molecules

    4. Between the slight negative charge of hydrogen and slight positive charge of oxygen in separate water molecules

Ans: C

6.The diagram illustrates two polysaccharides, resulting from the condensation of numerous glucose molecules. What are the designated names for X and Y?

 

 

X

Y

A

glycogen

amylose

B

 amylopectin

amylase

C

amylase

glycogen

D

amylose

amylopectin

Ans: A

7. Which description accurately characterises the genome and proteome?

    1. Gel electrophoresis exclusively analyses the genome, not the proteome.

    2. The genome and proteome exhibit uniformity across all organism tissues.

    3. The genome remains consistent, while the proteome differs among various tissues

    4. Variability arises solely from mutations in the proteome, not the genome.

Ans: C

8. Consider a short segment of DNA with the given base sequences for DNA strand 1 (A-C-G-G-C-A-T-T-A-G-C-T-A), DNA strand 2 (T-G-C-C-G-T-A-A-T-C-G-A-T), mRNA (U-G-C-C-G-U-A-A-U-C-G-A-U), and a tRNA anticodon (U-U-A). Identify the strand of DNA that undergoes transcription and specify the mRNA codon to which the tRNA anticodon (U-U-A) would bind during translation.

 

DNA strand transcribed

mRNA codon that tRNA anticodon binds to

A

DNA strand 1

second

B

DNA strand 2

second

C

DNA strand 1

third

D

DNA strand 2

third

Ans: C

9.What is the representation of the dashed line in the temperature-activity graph of the enzyme?

                     

 

    1. Increasing temperature increases substrate concentration.

    2. Increasing temperature affects the active site.

    3. Increasing temperature increases the rate of reaction.

    4. Increasing temperature decreases the movement of particles.

Ans: B

10.What type of fatty acid is shown?

    1. Trans unsaturated

    2. Cis unsaturated

    3. Trans saturated

    4. Cis saturated

      Ans: B

 

11.In exploring the chemical nature of genes, Hershey and Chase employed a bacteriophage for their investigation. They radioactively labeled sulphur in proteins and phosphorus in DNA. After bacterial infection and centrifugation, the data obtained from the experiment are displayed in the table.

Sample source

Supernatant

Pellet

Radioactive sulphur

80 %

20 %

Radioactive phosphorus

30 %

70 %

Following their experiment, what conclusion did Hershey and Chase draw?

    1. DNA was mainly outside the bacterial cells.

    2. Viruses infect bacterial cells with proteins.

    3. Viral DNA was found within the bacterial cells.

    4. Neither protein nor DNA were chemicals making up genes in viruses.

Ans: C

12. What are the primary role of DNA primase and DNA polymerase I in DNA replication?

  1.  

    DNA primase

    DNA polymerase I

    A

    adds a short DNA primer to the template strand

    replaces RNA with DNA in the Okazaki fragments

    B

     adds a short DNA primer to the template strand

    replaces DNA primers with RNA

    C

     adds a short RNA primer to the template strand

    replaces RNA with DNA in the Okazaki fragments

    D

    adds a short RNA primer to the template strand

    replaces RNA primers with DNA

    Ans: D

 

13.Why are dideoxyribonucleotides utilized to terminate sequences in base sequencing?

    1. Nucleotides cannot form 5′ to 3′ linkages with dideoxyribonucleotides.

    2. Nucleotides cannot form base pairs with dideoxyribonucleotides.

    3. Dideoxyribonucleotides cannot form hydrogen bonds with deoxyribose.

    4. Dideoxyribonucleotides do not have all four nitrogenous bases.

Ans: A

14. Which statement applies to DNA base sequences?

  1. Some genes do not code for proteins.

  2. Promoters are transcribed along with the gene.

  3. Introns are only found within genes coding for proteins.

    1. I only

    2. II only

    3. II and III only

    4. I, II and III

      Ans: B

 

15.How many carbon atoms are present in alpha-ketoglutarate and acetylCoA in the Krebs cycle?

Ans: A

16.Match the following proteins with their function:

 

Protein

Function

A

collagen

provides strength and support for tissues and organs

B

rhodopsin

enzyme found in tears

C

insulin

raises blood glucose concentrations

D

immunoglobulin

helps in blood clotting

Ans: A

17. 

             

What is the cell division stage shown in the diagram?

    1. Anaphase I of mitosis

    2. Anaphase II of mitosis

    3. Anaphase I of meiosis

    4. Anaphase II of meiosis

  2. Ans: D

18.In the pedigree chart depicting a family affected by cystic fibrosis, what is the likely genotype of the affected boy’s father?

 

  1. AA only

  2. Either AA or Aa

  3. Aa only

  4. aa only

Ans: C

19.Why can organs be transferred between any two cheetah individuals without rejection?

    1. Cheetahs exhibit poor reproductive success.

    2. Cheetahs possesses high heterozygosity.

    3. Cheetahs maintain a large gene pool.

    4. Cheetahs exhibit a small gene pool.

Ans: D

20.In their early 20th-century genetics studies, William Bateson and Reginald Punnett utilized the sweet pea (Lathyrus odoratus). They crossed pure-breeding plants with purple flowers and long pollen grains with those having red flowers and round pollen grains. The F1 generation showed uniformity with all plants having purple flowers and long pollen grains. Subsequently, crossing two F1 plants led to the F2 generation. What is a plausible explanation for the observed phenotypic ratio in the F2 generation?

Flower colour

Pollen grain shape

Number of plants

purple

long

4831

purple

round

390

red

long

393

red

round

1138

 

    1. Purple flowers and long pollen grains exhibit dominance, and the alleles assort independently.

    2. The genes controlling flower color and pollen shape are linked, with all long pollen grain plants being recombinants.

    3. The genes for flower color and pollen shape are linked, and all red flower plants are recombinants. 

    4. Plants with purple flowers and round pollen grains result from crossing over.

      Ans: D

 

21.What could be the cause of the perceived impact of genetically modified Bt maize on the monarch butterfly in the USA?

    1. The monarch butterfly consumes Bt toxin present in maize nectar.

    2. The monarch caterpillar ingests Bt toxin from maize leaves.

    3. Bt toxin eliminates the plants that the monarch caterpillar typically consumes.

    4. Bt toxin is present in maize pollen, which disperses onto plants eaten by the monarch caterpillar.

Ans: D

22. Two restriction endonuclease (EcoRI and BamHI) were used to cut a DNA sample into

smaller fragments.Based on the gel electrophoresis results, which statement finds support?

               

Which statement is supported by the data?

    1. The DNA sample is roughly 16 kb in size.

    2. Each endonuclease generates a 2 kb fragment.

    3. Both endonuclease yield the same number of fragments.

    4. The fragments produced using both endonuclease are all distinct from those produced

      by the individual endonuclease.

Ans: A

23. In the global carbon cycle, which components serve as the largest sink and flux, respectively?

 

Sink

Flux

A

atmosphere

combustion

B

oceans

respiration

C

oceans

photosynthesis

D

limestone

photosynthesis

Ans: C

24. In the transfer of carbon from producers to consumers in an ecosystem, in what form is carbon transferred?

  1. Carbon dioxide

  2. Protein

  3. Hydrogencarbonate ions

    1. I only

    2. II only

    3. I and II only

    4. I and III only

      Ans: B

 

25. The Silver Springs in Florida contribute to the Silver River. The provided diagram illustrates an energy pyramid for the Silver Springs ecosystem, with units in kJ  m–2 y–1.

               

 

I

III

A

sunlight

secondary consumer

B

producer

tertiary consumer

C

producer

secondary consumer

D

primary consumer

tertiary consumer

Ans: C

26. What conclusion can be inferred from the cladogram based on biochemical evidence?

                     

 

    1. Primates and Sirenia did not evolve from a common ancestor.

    2. Primates and Cetacea do not belong to any clade.

    3. Cetacea is less closely related to Sirenia than to Primates.

    4. Xenarthra has not undergone evolution for a longer duration compared to other clades.

      Ans: C

 

27. If seeds of an unidentified plant species are found, what assumption could be reasonably made about the species?

    1. Its male gametes are contained within pollen.

    2. Its seeds are contained within fruits.

    3. It is in the domain archaea.

    4. It is in the phylum angiospermophyta.

Ans: A

28. In ascending order of increasing numbers of species, what is the hierarchy of taxa?

    1. genus, family, order, class

    2. class, order, genus, family

    3. genus, family, class, order

    4. class, order, family, genus

      Ans: A

 

29. During a heartbeat, what leads to the closure of the atrioventricular valves?

    1. Pressure in the atria is higher than in the ventricles.

    2. Pressure in the atria is lower than in the ventricles.

    3. Pressure in the arteries is higher than in the ventricles.

    4. Pressure in the arteries is lower than in the ventricles.

      Ans: B

 

30. What specific observation did William Harvey use as evidence to support the concept of blood circulation?

    1. The ventricles of the heart pump blood out into arteries.

    2. Valves ensure unidirectional flow of blood.

    3. Capillaries carry blood from arteries to veins.

    4. All organs of the body have a separate blood supply.

Ans: B

31. Which numbers on the diagram correspond to a gland providing fluid for sperm and a tube dedicated to transporting sperm?

 

Gland providing fluid for sperm

Tube transporting sperm only

A

1

2

B

5

3

C

4

3

D

5

2

Ans: D

32. Among the hormones insulin, glucagon, thyroxin, and leptin, which hormone enhances the rate of energy release and utilization?

    1. Insulin

    2. Glucagon

    3. Thyroxin

    4. Leptin

Ans: C

33. Function of the loop of Henle:

    1. To reabsorb salt

    2. To maintain a hypertonic solution in the medulla

    3. To transport liquid from the collecting ducts to the convoluted tubules

    4. To reabsorb glucose

      Ans: B

 

34. Insects typically excrete uric acid as their nitrogenous waste in which form ?

    1. Urea

    2. Uric acid

    3. Ammonia

    4. Urine

      Ans: B

 

35. What characteristics do mammalian endoskeletons and insect exoskeletons share?

    1. They are both made of bone.

    2. They both have cartilage.

    3. They are both moved by antagonistic sets of muscles.

    4. Both consist of dead tissue.

Ans: C

36.After testing positive for anti-D, the man underwent ABO blood group testing. What is the ABO blood group of the individual who tested positive for anti-D, according to the obtained results?

What ABO blood group does the man testing positive for anti-D have?

    1. A

    2. B

    3. AB

    4. O

      Ans: D

 

37. In ascending order of size, what is the sequence for muscle structures?

    1. muscle, muscle fibre, myofibril, sarcomere

    2. myofibril, muscle fibre, sarcomere, muscle

    3. sarcomere, myofibril, muscle fibre, muscle

    4. muscle fibre, sarcomere, myofibril, muscle

Ans: C

38. Which characteristic in the cross-section of an Ammophila leaf indicates its adaptation as a xerophyte?

    1. The leaf surface area is increased.

    2. The rolled leaf reduces the upper epidermis area.

    3. The rolled leaf protects the lower epidermis from the wind.

    4. The lower epidermis can transpire more easily.

      Ans: C

 

39. 

                       

What are the structures labelled X and Y?

 

X

Y

A

developing bud

xylem

B

developing leaf

xylem

C

developing bud

meristem

D

developing leaf

meristem

Ans: D

40. In a technique for measuring flow rates in phloem, what could be utilised?

I Potometers

II Aphid stylets

III 14C02

A I and II only
B. I and III only
C. II only
D. II and III only

  1. Ans: D
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