| Date | May 2018 | Marks available | 4 | Reference code | 18M.2.HL.TZ1.8 |
| Level | Higher level | Paper | Paper 2 | Time zone | Time zone 1 |
| Command term | Outline | Question number | 8 | Adapted from | N/A |
Question
Describe the process of spermatogenesis leading to the production of four sperm cells in a human male.
Outline the roles of estrogen and progesterone in females during human reproduction.
Explain the process of muscle contraction.
Markscheme
a. in the seminiferous tubule
b. diploid cells/spermatogonia grow/enlarge
c. two divisions of meiosis
d. primary spermatocyte carries out the first division and secondary spermatocytes carry out the second division
e. meiosis produces haploid cells/spermatids
f. haploid cells/spermatids differentiate into spermatozoa/sperm cells
OR
develop tail/flagellum/helical mitochondrion/acrosome/sac of enzymes
g. Sertoli cells help sperm to mature/differentiate
Allow answers presented in a clearly annotated diagram.
a. estrogen/progesterone for repair/thickening/development/vascularisation of uterus lining/endometrium
b. estrogen (at high levels) stimulates LH secretion (which stimulates ovulation)
c. progesterone maintains the uterus lining/endometrium during pregnancy/prevents miscarriage
d. progesterone/estrogen inhibits FSH/LH secretion
e. progesterone for development of breast tissue during pregnancy
f. fall in progesterone/rise in estrogen leads to labour/contractions/childbirth
g. estrogen/progesterone cause pre-natal development of female reproductive organs
OR
h. estrogen/progesterone cause secondary sexual characteristics
a. muscle fibre contains many myofibrils
b. made up of sarcomeres/labelled diagram showing one or more sarcomeres
c. nerve impulse/signal from (motor) neuron causes release of calcium (ions)/Ca2+
d. calcium (ions)/Ca2+ released from sarcoplasmic reticulum
e. calcium (ions)/Ca2+ link to troponin
f. tropomyosin moves to expose actin binding sites
g. ATP hydrolysis/ATP to ADP and phosphate/release of phosphate from ATP
h. ATP binds to myosin heads and causes them to cock/change angle/release/gain energy
i. myosin heads bind/form cross-bridges to actin
j. myosin heads push on actin and then detach from actin
k. actin moved towards centre of sarcomere/sliding of filaments
l. sarcomere becomes shorter (resulting in muscle contraction)
Accept any mark point if clearly made on an annotated diagram.
Examiners report
Syllabus sections
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17N.1.HL.TZ0.40:
The diagram shows the female reproductive system.
[Source: © International Baccalaureate Organization 2017]
Which structures do K and L identify?
- 22M.1.HL.TZ1.40: What is the role of HCG in early pregnancy? A. It prevents the degeneration of the corpus...
- 22M.1.HL.TZ1.37: Which mechanism prevents polyspermy? A. Polar body formation B. The acrosome reaction C....
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20N.1.HL.TZ0.39:
The diagram shows a section through a seminiferous tubule.
[Source: © International Baccalaureate Organization 2020.]
Which labelled cells are diploid and haploid, respectively?
- 18N.1.HL.TZ0.39: The image shows a flow chart. Which sequence would correspond to the stages shown in the...
- 17M.1.HL.TZ1.38: Which hormone is inhibited during pregnancy in order to prevent contractions of the...
- 16N.1.HL.TZ0.40: Where does the acrosome reaction occur?
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19M.1.HL.TZ1.36:
The diagram shows the chromosomes derived from a single homologous pair following meiosis in a diploid cell.
Which diagram represents the homologous pair from which these chromosomes were derived?
[Source: © International Baccalaureate Organization 2019]
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19M.1.HL.TZ1.40:
The image shows a light micrograph of tissue stained with a dye that binds to the nucleic acids in a cell.
[Source: by Jose Luis Calvo/Shutterstock]
What is the major purpose of the tissue depicted in the image?
A. Absorption of digested food
B. Production of insulin
C. Spermatogenesis
D. Fertilization
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17N.2.HL.TZ0.06b:
Cell biologists play an important role in research into disease, fertility, evolution and many
other areas of science.Compare and contrast the processes of spermatogenesis and oogenesis.
- 17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
- 22M.1.HL.TZ2.40: Hormones maintain the thickness of the endometrium during pregnancy. However, insufficient...
- 17M.1.HL.TZ2.39: What does the blastocyst secrete? A. HCG B. Estrogen C. ADH D. Progesterone
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21N.1.HL.TZ1.40:
The micrograph shows part of a human sperm cell. Which region of the cell is responsible for the greatest production of ATP?
[Source: Oliveira, J.B.A., Petersen, C.G., Massaro, F.C. et al. Motile sperm organelle morphology examination (MSOME):
intervariation study of normal sperm and sperm with large nuclear vacuoles. Reprod Biol Endocrinol 8, 56 (2010).
https://doi.org/10.1186/1477-7827-8-56. https://embryology.med.unsw.edu.au/embryology/index.php/File:Single_
human_spermatozoa.jpg Creative Commons Attribution License (CC BY 2.0) (http://creativecommons.org/licenses/
by/2.0).] -
21N.2.HL.TZ0.2d:
Explain the mechanism that prevents polyspermy during fertilization.
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19N.1.HL.TZ0.40:
The diagram shows a section through the seminiferous tubules. What is the cell labelled X?
[Source: © International Baccalaureate Organization 2019]
A. Spermatid that will differentiate into sperm
B. Primary spermatocyte that will undergo meiosis to form secondary spermatocytes
C. Sertoli cell that provides nutrients
D. Stem cell that will divide by mitosis to form spermatogonia
- 17M.1.HL.TZ2.40: What helps to prevent polyspermy? A. The unequal division of oocytes B. The placental...
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21M.1.HL.TZ1.39:
The pregnancy test for humans is based on detection of the hormone HCG. What is the reason for detection of this hormone indicating pregnancy?
A. HCG is involved in milk production.
B. HCG production is blocked by negative feedback during menstruation.
C. HCG is produced by an embryo.
D. HCG is released during the acrosome reaction.
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20N.1.HL.TZ0.40:
The graph shows three hormones circulating during pregnancy in the rat, with birth occurring at 22 days.
[Source: Dr Paul Kenyon University of Plymouth (retired).]
What are hormones X and Z?
- 17M.2.HL.TZ2.7b: Describe the different cell types in the seminiferous tubules that are involved in the...
- 18M.1.HL.TZ2.40: Which interaction occurs between hormones in the reproductive systems of women? A. Estrogen...
- 18N.1.HL.TZ0.40: If the ovaries of a pregnant woman have to be removed during the first five months of...
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21M.1.HL.TZ2.40:
What function is maintained as a result of the release of HCG?
A. Production of milk by the mammary glands
B. Release of oxytocin by the posterior pituitary gland
C. Production of FSH by the anterior pituitary gland
D. Production of progesterone by the ovary
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17N.3.HL.TZ0.02a:
Concerns have been raised about the effect of rising pollution levels on sperm production in men. To investigate the possible effects of pollution on spermatogenesis, sperm samples from men of similar ages were collected in Kolkata in the 1980s and 2000s. The box plot represents the mean and range of sperm counts in the 1980s and 2000s.
[Source: Republished with permission of Elsevier Science and Technology Journals, from ‘Semen quality and age-specific changes: A study between two decades on 3729 male partners of couples with normal sperm count and attending an andrology laboratory for infertility-related problems in an Indian city’, Dyutiman Mukhopadhyay, Alex C. Varghese, Manisha Pal, Sudip K. Banerjee, Asok K. Bhattacharyya, Rakesh K. Sharma, and Ashok Agarwal, Fertility and Sterility, 93 (7), 2009; permission conveyed through Copyright Clearance Center, Inc]
A hypothesis has been suggested that pollution may have a negative effect on spermatogenesis. Evaluate whether the data support this hypothesis.
- 17M.1.HL.TZ1.40: The diagram shows the exchange processes that take place in the placenta between the maternal...
