Ib Biology 1

1. The diagram below represents the results obtained in a DNA profile from a crime scene Suspect 2 is most likely to be the criminal because the band pattern coincides with that of the crime scene sample. What do these bands represent?

DNA fragments

Genes

Chromosomes

Chromatids

2. How can cells in a multicellular organism differentiate?

They express some of their genes but not others.

They all have a different genetic composition.

Different cells contain a different set of chromosomes.

Different cells do not have some of the genes.

3. Which feature increases the absorption of glucose in the small intestine?

Villi

Lacteal

Cilia

Goblet cells

4. The diagram below shows the structure of a chloroplast What is the structure labelled X?

Ribosome

Stroma

Inner membrane

Thylakoid

5. Which of the following is a function of cellulose in plants?

Storage of fat

Formation of mitochondria

Storage of energy

Formation of cell walls

6. What do the graphs below show?

Population in the United States is increasing at a higher rate.

Infant death rate is high in both countries.

Males live longer than females in both countries.

Birth rate is higher in Mexico than in the United States.

7. Why is light important in photosynthesis?

To produce ATP and split water molecules

To produce ADP needed to fix carbon dioxide

To activate the enzymes that fix carbon dioxide

To activate carbon dioxide molecules

8. What does a small standard deviation signify?

The data is not correlated.

The data is widely spread around the mean.

The data shows a close relationship between two variables.

The data is clustered closely to the mean value.

9. The table below shows the codons that determine different amino acids in protein translation. What is the sequence of the amino acids that is being translated from the following mRNA sequence? 5′ AUGGGUGCUUAUUGGUAA 3′

Met-Pro-Arg-Ile-Thr

Met-Cys-Ser-Tyr-Trp

Met-Gly-Ala-Tyr-Trp

Met-Gly-Tyr-Ala-Thr

10. Which of the following forms the nucleosome?

DNA and histone molecules

DNA only

RNA and histone molecules

Histone molecules only

11. What is a role of sulfur in living organisms?

Formation of proteins

Formation of carbohydrates

Formation of teeth

Transmission of nerve impulses

12. The graph below shows the effect of temperature on the separation of the strands in DNA to form single strands. The temperature at which 50 % of the DNA is single-stranded is called the melting temperature (TM ). What do the results show?

When the temperature reaches 85 °C there are no more double-stranded DNA molecules.

When the temperature reaches 85 °C the DNA strands start separating rapidly.

A TM of 85 °C means that DNA is not stable at room temperature (25 °C).

The separation of the DNA strands is directly proportional to the increase in temperature.

13. What is the function of the cytoplasmic (plasma) membrane of this bacterium?

To produce ADP

To form the only protective layer preventing damage from outside

To control entry and exit of substances

To synthesize proteins

14. What does the universal nature of the genetic code allow?

Change of genetic code in the same species

Transfer of genes between species

Formation of clones

Infection by bacteria

15. The diagram below shows water in the human body. Where in the digestive system is the largest volume of water absorbed from?

Colon

Pancreas

Small intestine

Liver

16. Which of the following is a characteristic of platyhelminthes?

Many pairs of legs

Flat body

Hard exoskeleton

Presence of cnidocytes

17. Which of the following is the cause of sickle-cell anemia?

Tryptophan is replaced by leucine

Leucine is replaced by valine

Glutamic acid is replaced by valine

Lysine is replaced by glutamic acid.

18. Why are antibiotics effective against bacteria?

They can produce specific antibodies.

They can engulf foreign matter

They can block specific metabolic pathways.

They can act as a vaccine.

19. What is a genetic test cross?

Testing a suspected homozygote by crossing it with a known heterozygote

Testing a suspected heterozygote by crossing it with a known heterozygote

Testing a suspected homozygote by crossing it with a known homozygous dominant

Testing a suspected heterozygote by crossing it with a known homozygous recessive

20. What kind of inheritance does skin colour represent?

Sex-linked (X-linked)

Multiple alleles

Systemic

Polygenic

21. Which of the following is a consequence of global temperature rise on arctic ecosystems?

Increased rates of decomposition of detritus trapped in permafrost

Decrease of geographical range of habitats for temperate species

Decrease of pest species and increase of permafrost species

Increase of geographical range of habitats for permafrost species

22. Which of the following features of the alveoli adapt them to gaseous exchange? I. Single layer of cells II. Film of moisture III. Dense network of capillaries

I and II only

II only

II and III only

I, II and III

23. Which phylum does the plant below belong to?

Angiospermophyta

Bryophyta

Coniferophyta

Filicinophyta

24. How can active immunity be acquired?

By having the disease

Injection of antibodies

Through colostrum

Via placenta

25. What is a cause of the plateau phase in a population growth curve?

Excess of food

Disease

Increase in prey

More space availability

26. Which of the following are characteristics of monocotyledonous plants? I. Parallel venation of leaves II. Floral organs in multiples of four III. Fibrous adventitious roots

I and II only

I and III only

II and III only

I, II and III

27. Which hormone causes the closing of stomata?

Abscisic acid

Gibberellin

Auxin

Ethylene

28. What is a role of the pacemaker or sinoatrial node (SAN)?

To initiate contraction of the ventricle

To pass the excitation through Purkinje fibres

To originate excitation in myogenic muscle

To cause the relaxation of the atria

29. What are fused in the production of monoclonal antibodies?

Tumour cells and T-cells

Tumour cells and B-cells

B-cells and T-cells

Antibodies and antigens

30. What is the link reaction in aerobic respiration?

Pyruvate is carboxylated, acetyl reacts with coenzyme A, reducing NADH + H+

Pyruvate is decarboxylated, acetyl reacts with coenzyme A, forming NADH + H+

Pyruvate reacts with coenzyme A, forming NADH + H+

Pyruvate is decarboxylated, reacting with coenzyme A, reducing NADH + H+

31. What happens during the G2 stage of interphase?

Homologous chromosomes pair

Synthesis of proteins

Homologous chromosomes separate

Replication of DNA

32. In a cell, what is the effect of a large surface area to volume ratio?

Slower rate of exchange of waste materials

Faster heat loss

Faster rate of mitosis

Slower intake of food

33. Which of the following best describes what happens in the glomerulus?

Selective reabsorption of water and molecules by active transport

Ultrafiltration introduces water and other molecules into the capillaries

Regulation of salt balance leading to the production of urine

High blood pressure forces water and other molecules into the nephron

34. Why is oxaloacetate a competitive inhibitor?

It causes a conformational change to the active site.

It binds to the enzyme away from the active site.

It is structurally similar to succinate.

It is structurally similar to succinate dehydrogenase

35. How do mineral ions in the soil move to the root through the soil?

Osmosis

Mass flow of water

Translocation

Through phloem

36. The diagram below shows the side view of the arm joint . Which letter is pointing to the ulna?

W

X

Y

Z

37. Which are the possible recombinants in a dihybrid test cross involving the linked genes

38. What happens during the formation of Okazaki fragments?

DNA polymerase III adds nucleotides in the 3′→5′ direction.

DNA polymerase III adds nucleotides in the 5′→3′ direction.

DNA polymerase I adds nucleotides in the 5′→3′ direction.

RNA polymerase adds nucleotides in the 3′→5′ direction.

39. Which pair of statements best describes oogenesis and spermatogenesis? Oogenesis Spermatogenesis

40. What is chemiosmosis?

Coupling of ATP synthesis to the electron transport and proton movement

Phosphorylation of glucose in the mitochondrial matrix

H + ions moving down a concentration gradient into the mitochondrial matrix

Activation of ATPase in order to synthesize ATP

IB Biology 1