Home / 2019 May Biology paper 1 TZ2 SL- Concept Questions and Answer

2019 May Biology paper 1 TZ2 SL- Concept Questions and Answer

  1. Which structures are found only in prokaryotic cells?

    1. Ribosomes

    2. Pili

    3. Cell walls

    4. Flagella

      Ans: B

2 . The magnification of the micrograph is 2000×.

[Source: https://upload.wikimedia.org/wikipedia/commons/6/6c/HeLa_cells_stained_with_Hoechst_33258.jpg by TenOfAllTrades.]

What is the maximum diameter of the nucleus in the cell labelled X?

    1. 10 μm

    2. 10 nm

    3. 20 μm

    4. 20 nm

Ans: A

3. The image shows a micrograph of a cell.

                                         

[Source: © 2014, https://commons.wikimedia.org/wiki/File:Mitosis_(261_13)_Pressed;_root_meristem_of_onion_(cells_ in_prophase,_metaphase,_anaphase,_telophase).jpg by Doc. RNDr. Josef Reischig, CSc.]

What explains the 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

 

4. Which processes are involved 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

5. The table shows concentrations of potassium ions 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

What explains these concentrations?

    1. Potassium ions diffuse in and sodium ions diffuse out.

    2. Sodium ions diffuse in and potassium ions diffuse out.

    3. Active transport pumps sodium ions in and potassium ions out.

    4. Active transport pumps sodium ions out and potassium ions in.

Ans: D

6. Where 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 different water molecules

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

Ans: C

7. The diagram shows two polysaccharides, formed from condensation of many glucose molecules.

[Source: © International Baccalaureate Organization 2019]

What are the names of X and Y?

X

Y

A glycogen

amylose

B amylopectin

amylase

C amylase

glycogen

D amylose

amylopectin

Ans: A

8. Which statement correctly describes genome and proteome?

    1. Only the genome but not the proteome can be analysed using gel electrophoresis.

    2. The genome and the proteome are the same in all tissues in an organism.

    3. In cells of different tissues, the genome is the same while the proteome varies.

    4. Only mutations in the proteome but not in the genome cause any variability.

Ans: C

9. The base sequences of a short section of DNA are shown, together with mRNA that has been

transcribed from it and one of the tRNA anticodons that could be used to translate the mRNA.

DNA strand 1 A-C-G-G-C-A-T-T-A-G-C-T-A tRNA anticodon U-U-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

Which strand of DNA is transcribed and to which codon in the mRNA would the tRNA anticodon

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

10. Lactose intolerance occurs when the enzyme, lactase, that digests lactose is not produced after

infancy in humans. The incidence of lactose intolerance varies in different racial groups. The graph

shows the distribution of lactose intolerance in different human populations.

                                   

What can be hypothesized from the graph?

    1. Native American people produce most lactase after infancy.

    2. Most Indian people do not produce lactase after infancy.

    3. Lactase is not produced after infancy in most Caucasian people.

    4. One quarter of Afro-Caribbean people will probably experience digestive problems when drinking milk.

Ans: B

11. The graph shows the absorption spectra of chlorophyll a and chlorophyll b.

                                         

What can be concluded from the graph?

    1. Both chlorophyll a and chlorophyll b absorb a large amount of green light

    2. Chlorophyll b absorbs red light more efficiently than blue light

    3. Other pigments must absorb light between blue and red in the spectrum

    4. Chlorophyll a and chlorophyll b have different absorption peaks

      Ans: D

12. The diagram shows a type of fatty acid.

             

What type of fatty acid is shown?

    1. Trans unsaturated

    2. Cis unsaturated

    3. Trans saturated

    4. Cis saturated

Ans: B

13. The graph shows the incidence of trisomy resulting from non-disjunction in pregnancies at

different maternal ages.

                         

What can be inferred from the graph?

    1. The incidence of three copies of a chromosome increases directly in proportion with the age of the mother.

    2. The incidence of three sets of chromosomes increases from age 20.

    3. The incidence of three copies of a chromosome increases the most from age 35.

    4. The incidence of three sets of chromosomes increases the most from age 30.

Ans: C

14. The pedigree chart shows a family affected by cystic fibrosis.

What is the genotype of the affected boy’s father?

  1. AA only

  2. Either AA or Aa

  3. Aa only

  4. aa only

Ans: C

15. The children in a family have blood groups A, B and O. What are the genotypes of their parents?

    1. IAIA and IBi

    2. IAi and IBi

    3. IAIB and ii

    4. IAIB and IBi

Ans: B

16. Genetically modified maize, called Bt maize, is thought to be affecting the monarch

butterfly (Danaus plexippus) in the USA. What is the reason for this?

    1. The monarch butterfly feeds on maize nectar, which contains Bt toxin.

    2. The monarch caterpillar feeds on maize leaves, which contain Bt toxin.

    3. Bt toxin kills the plants that the monarch caterpillar usually eats.

    4. Bt toxin is in maize pollen, which blows on to plants that the monarch caterpillar eats.

Ans: D

17. In an ecosystem, in the transfer of carbon from producers to consumers, what is carbon

transferred as?

  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

 

18. The Silver Springs feed into the Silver River in Florida. The diagram shows a pyramid of energy

for the Silver Springs ecosystem. The units are kJ  m–2  y–1.

What do level I and level III represent in the pyramid of energy?

I

III

A sunlight

secondary consumer

B producer

tertiary consumer

C producer

secondary consumer

D primary consumer

tertiary consumer

Ans: C

19+. Which is not essential in a viable mesocosm?

    1. Light source

    2. Autotroph

    3. Saprotroph

    4. Herbivore

Ans: D

20. What is required for natural selection to occur?

  1. Acquired characteristics

  2. Advantageous characteristics

  3. Genetic variation

    1. I only

    2. I and III only

    3. II and III only

    4. I, II and III

Ans: C

21. If seeds of an unknown species of plant are discovered, what assumption can be 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

22. Which phyla have bilateral symmetry?

    1. annelida, arthropoda, platyhelmintha

    2. porifera, arthropoda, platyhelmintha

    3. cnidaria, porifera, mollusca

    4. porifera, annelida, mollusca

Ans: A

23. Which is the hierarchy of taxa in order of decreasing numbers of species?

    1. domain, phylum, order, family

    2. phylum, order, family, class

    3. domain, phylum, order, class

    4. phylum, class, family, order

      Ans: A

 

24. What is an advantage of capillary walls being one cell thick in the systemic circulation?

    1. To allow carbon dioxide to diffuse into tissues

    2. To allow oxygen to diffuse out of tissues

    3. To allow glucose to diffuse into tissues

    4. To allow urea to diffuse into tissues

Ans: C

25. What causes the atrioventricular valves to close during a heartbeat?

    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

26. In premature babies born earlier than the 30th week of pregnancy, type II

pneumocytes are usually not fully developed, so they do not carry out their function normally.

What is a possible consequence of this?

    1. The number of alveoli reduces.

    2. The size of the alveoli increases.

    3. Capillary networks do not develop fully and oxygen is not absorbed.

    4. Surface tension between alveoli does not decrease and the alveoli stick together.

Ans: D

27. What is the reason for antibiotics not damaging human cells?

    1. The dose is too small to be harmful.

    2. The dose is taken for only a short time.

    3. Antibiotics occur naturally in humans.

    4. Human metabolism is different from bacterial metabolism.

Ans: D

28. The diagram shows a motor neuron.

                 

What are the biochemical nature and function of the myelin sheath?

    1. The myelin sheath is mainly protein which allows growth of the axon.

    2. The myelin sheath is mainly protein which acts as membrane carriers.

    3. The myelin sheath is mainly lipid which allows saltatory conduction.

    4. The myelin sheath is mainly lipid which provides an energy source.

Ans: C

29. Which hormone is part of a negative feedback control system and acts on cells in the hypothalamus?

    1. Insulin

    2. Glucagon

    3. Melatonin

    4. Leptin

Ans: D

30. The diagram shows the human female reproductive system.

                     

Which labels indicate where fertilization occurs and where luteinizing hormone (LH) acts?

Where fertilization occurs

Where LH acts

1

3

2

5

3

4

1

5

Ans: D

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