Syllabus Edition

First teaching 2023

First exams 2025

|

Reproduction (SL IB Biology)

Exam Questions

2 hours39 questions
1a
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1 mark

The process of reproduction is controlled by a series of hormones. The graph below shows changes in the levels of reproductive hormones A-D in females during a single menstrual cycle.

1-3

Identify, with a reason, the hormone represented by line A.

1b
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2 marks

Line C represents the hormone progesterone.

(i)

Identify the source of the hormone progesterone during the regular menstrual cycle.

[1]

(ii)

State one role of progesterone.

[1]

1c
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2 marks

A common treatment for fertility problems is in vitro fertilisation, or IVF. During IVF a woman will be given medication containing the hormone FSH.

Explain why medication containing FSH is administered during IVF.

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2
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4 marks

Draw a labelled diagram of the female reproductive system.

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3a
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2 marks

The diagram shows a human egg and three sperm cells at the moment of fertilisation. 9WOrJSD6_e-2a

Suggest why the egg is so much larger than one sperm, even though they carry the same amount of genetic information as each other. 

3b
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1 mark

State the number of chromosomes in a human egg. 

3c
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1 mark

Name the cell that forms when a sperm fertilises an egg. 

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4a
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3 marks

The image below shows a bee feeding on nectar from a flower. 

(I)
Identify the small specks indicated X

bee-pollinating---sq

[1]

(II)
Explain how the flower benefits from feeding nectar to insects such as bees.

[2]

4b
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1 mark

State the name of the type of relationship that exists between the bee and the flower in part c) of this question.  

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5a
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2 marks

Gregor Mendel's landmark experiments on the basis of genetic inheritance, involved the flowering plant the sweet pea (Lathyrus odoratus). In these experiments, Mendel transferred the male sexual organs of certain plants to the female sexual organs of separate plants as a way of performing crosses.

Before completing the transfer, he cut away the male sexual organs of the recipient plants before the transfer.

Explain why. 

5b
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6 marks

The image below shows a flower. 

flower-to-label---sq

Label the parts A - F indicated. 

5c
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1 mark

State the name of the part of the flower shown in part b) that receives pollen during sexual reproduction. 

5d
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2 marks

State the principal purpose of the:

(i) Petals

(ii) Sepal 

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6a
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3 marks

The diagram below shows two types of seed; sycamore and dandelion.

Seeds dispersed by wind - SQ

State the method by which these seeds are dispersed and in each case, one adaptation of the seed that allows effective dispersal.  

6b
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2 marks

Seeds such as those shown in part a) are more effective if they can be dispersed far away from the parent plant.

Explain why. 

6c
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2 marks
The coco de mer is a seed that comes from a type of palm tree native to the Seychelles. Lodoicea maldivica is the species that produces the largest seeds known in nature. One such seed was found that had a mass of 25kg. To show the scale, a coco de mer seed is pictured below in the hands of a human. 

coco-de-mer-seed---sq

Suggest why some plants like the dandelion and sycamore have small, lightweight seeds whereas others produce huge seeds like the coco de mer. 

6d
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2 marks

Describe how seeds found in fruit such as apple pips are dispersed. 

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1a
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2 marks

The diagram shows the female reproductive system in front view2ot7_qMw_1

Identify structures 1 and 2.

1b
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1 mark

State the function of structure 3 from part (a).

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2a
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2 marks

In vitro fertilisation, known as IVF, involves fertilisation of a female egg outside of the human body. The hormones FSH and LH are used in IVF.

State the functions of FSH and LH in IVF.

2b
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2 marks

A fertility clinic investigated the effect of body mass index (BMI) on the outcome of the percentage of women who had successful implantation, became and remained pregnant, and were able to take home a healthy baby following IVF treatment.

Their results are shown in the graph below.

t9PtZI23_3

The clinic advised women with a BMI greater than 30kg/m² to lose weight before embarking on IVF treatment.

Use the data to explain why.

2c
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1 mark

State what is meant by the term superovulation.

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3a
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5 marks

Outline the events that occur, including the hormones involved, during days 14-28 of the menstrual cycle in the absence of fertilisation.

3b
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3 marks

The hormone oestrogen is involved in both positive and negative feedback loops within the menstrual cycle.

Explain how oestrogen functions in both positive and negative feedback within the menstrual cycle.

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4
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2 marks

The life cycle of a flower involves a vegetative phase, during which the plant may be able to reproduce asexually, and a reproductive phase, during which sexual reproduction is possible.

Contrast asexual and sexual reproduction.

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5a
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2 marks

Explain why the relationship between flowering plants and pollinators can be considered mutualistic.

5b
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3 marks

The following diagram shows the reproductive parts of two flowers of the same species.

q2c_9-4_reproduction_in_plants_medium_ib_hl_biology_sq

   

Identify structures A to C and state how each contributes to the process of sexual reproduction in the plant.

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6a
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3 marks

Pollination is the first step in sexual reproduction in plants.

Describe the events that occur after a pollen grain lands on the stigma of a flower until fertilisation happens.

6b
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2 marks

The following table shows the number of honey bee colonies documented by a beekeeper on a farm from 2008 to 2018.

Year

Number of living colonies

2008

36

2010

34

2012

22

2014

23

2016

27

2018

21

 

Calculate the percentage decrease in bee colonies from 2008 to 2018.

6c
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3 marks

Suggest the impacts that a decline in pollinators would have on the wider ecosystem.

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7a
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2 marks

The following investigation was set up to determine the conditions needed for germination.

q4c_9-4_reproduction_in_plants_medium_ib_hl_biology_sq
           

Identify the control in this experiment and explain the importance of including this test tube in the investigation.

7b
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1 mark

Explain why no seeds would germinate if test tube D from the investigation at c) was placed in an environment with a temperature of 45°C.

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8
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3 marks

Outline the adaptations of seeds with different methods of seed dispersal in flowering plants.

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1a
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7 marks

Draw a labelled diagram of the male reproductive system.

1b
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8 marks

Describe the role of hormones in the regulation of the menstrual cycle.

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2a
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2 marks

A group of insects called flower thrips includes the species Frankliniella intonsa, as shown in the image below.

frankliniella-intonsa---sq

Adult F. intonsa flower thrips pollinate flowers of the genus Stellera in central and southern Asia. In return for the pollination it receives, Stellera provides sites for F. intonsa to lay their larvae (young).

State how this differs from a more conventional insect-flower mutualistic relationship. 

2b
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2 marks

Changes to abiotic conditions such as those caused by climate change can disrupt mutualism between pollinators and flowering plants. 

Suggest the consequences of extinction of a pollinator on other species. 

2c
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2 marks

A symbiotic relationship between two species is defined as any type of a close and long-term biological interaction between two different biological organisms.

The relationship between a bumblebee and the flowers it feeds from (and pollinates) is referred to as mutualistic.

Using this information, distinguish between symbiosis and mutualism.

2d
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1 mark

The best-documented examples of animal pollinators include bees and other insects. However, some larger animals are very active pollinators. 

One such animal is the honey possum (Tarsipes rostratus), a small marsupial native to southwestern Australia. Some of the pollen that a honey possum comes into contact with is used as a food, with all the available nutrients being used by the honey possum for its own dietary requirements.

honey-possum---sq

Suggest one adaptation, from the image above, of the honey possum that hints at its role as a pollinator. 

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3
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2 marks

Scientists investigated the link between PCOS in pregnant women and the risk of premature birth. The study was conducted in the maternity ward of a hospital and only women that had previously been diagnosed with PCOS were included in the PCOS group of the investigation. The results of the investigation are shown in the graph below.

preterm-birth-pcos-graph-sqpreterm-birth-pcos-graph-sq

Calculate the percentage difference between the PCOS and non-PCOS groups that delivered their babies between 32 and 35 weeks of pregnancy. Show your working.

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4
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2 marks

The graph below shows the relationship between body mass and gestation period for different species of mammals. 

body-size-vs-gestation-period-sq

The American black bear Ursus americanus is a large carnivore with an average body mass of 70 kg and a gestation period of 220 days.

Draw the data point for the black bear on the graph. Show your working.

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5a
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4 marks

Outline the events that take place during the germination of a seed.  

5b
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2 marks

In exploring the effects of subjecting germinating seeds to different growth conditions, the following experiment was set up.  

Method summary:

  • Set up 4 test tubes, each containing cress seeds on cotton wool
  • For test tube A, cotton wool left dry
  • For test tube B, add enough water to the cotton wool so that it becomes moist
  • For test tube C, add enough water to cover the cotton wool and seeds, then carefully add a layer of oil on top of the water
  • For test tube D, add enough water to the cotton wool so that it becomes moist
  • Leave tubes A, B and C at room temperature or incubated at a specific temperature e.g. 20 °C
  • Place tube D in a fridge at approximately 4 °C
  • Compare the results and see which tube has the greatest number of germinated seeds

Factors affecting germination - SQ

Outline the control variables that the scientists would need to adhere to in order to produce valid data. 

5c
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1 mark

Rather than counting the number of seeds that had germinated at the end of the experiment, suggest a more accurate measure of the dependent variable. 

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6
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5 marks

Compare and contrast the methods employed by plants for pollen distribution and seed dispersal.  

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