16.1 Reproduction in Plants & Humans

Some students investigated the conditions needed for the germination of maize seeds. They used maize seeds from a packet of seeds they had purchased in a shop.

Three dishes were used, each containing cotton wool and the same number of maize seeds, as shown in Fig. 1.

Fig. 1

Table 1 shows the conditions provided for each dish. 

Table 1

The seeds were left for five days and then observed.

The results are shown in Table 2

Table 2

[2]

In a second investigation, maize seeds were placed in a dish containing damp cotton wool.

This dish was left in the dark for five days at 20°C.

Predict and explain the results.

[2]

A student gathered 70 maize seeds from plants growing in a field. The seeds were placed in dishes containing damp cotton wool.

After five days, only 64 seeds had germinated. 

Calculate the percentage of seeds that germinated.

Show your working.

Give your answer to the nearest whole number. 

[2]

Suggest a reason why some of the seeds did not germinate.

[1]

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Polycystic ovary syndrome (PCOS) is a condition that commonly occurs in women of reproductive age. It is characterised by hormonal imbalances that affect the menstrual cycle of women with this condition.

Fig. 1 compares the levels of FSH and LH in a normal menstrual cycle with the levels seen in the cycle of a woman with PCOS.

Fig. 1

Use the information in Fig. 1 to explain the effect that PCOS would have on the ovaries of a woman.

[4]

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Women with PCOS will often struggle with infertility.

Suggest a possible reason for this.

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Fig. 2 shows changes in the thickening of the uterus wall lining in two women X and Y.

Fig. 2

Suggest an explanation for the difference in the thickness of the uterus wall lining between woman X and Y in Fig. 2.

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Outline how the levels of LH and progesterone will differ between woman X and Y during the next calendar month (assume a normal menstrual cycle for woman Y). 

Some insects can reproduce by sexual reproduction and asexual reproduction. In both types of reproduction chromosomes are passed from the parent or parents, to the offspring.

Fig. 1 shows a drawing of a parent insect and seven of her offspring: M, N, P, R, S, T and U.

Fig 1

Two of the offspring were produced by asexual reproduction.

Suggest the letters representing these two offspring.

[1]

Insect R was produced by sexual reproduction.

Use the information from the diagram to support this statement.

State the term that is defined as the observable features of an organism.

[1]

Complete the sentences by stating the part of the human body that produces male gametes and the part that produces female gametes.

Male gametes are produced by the ........................................................................

Female gametes are produced by the ...................................................................

Fig. 1 represents the early stages in the development of a female embryo.

Fig. 1

[3]

Fig. 1 shows a section through a flower.

Fig. 1

Write one letter from Fig. 1 to identify each of the following.

You may use each letter once, more than once, or not at all.

[6]

Fig. 2 shows pollen grains from the flowers of several different species, labelled with the letters K–Q.

Fig. 2

State the letters of the pollen grains that come from insect-pollinated flowers.

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Sugarcane is a crop plant that is usually grown from stem cuttings rather than from seeds.

Describe the advantages of using cuttings rather than seeds to reproduce crop plants.

Define the term sexual reproduction.

Fig. 1 shows some organs in the body of a man.

Fig. 1

Complete Table 1 by writing in the names of the parts labelled A to D in Fig. 1. 

Table 1

[4]

State the function of the scrotum.

Fig. 1 shows sections of two flowers, K and L, from the same species.

Fig. 1

[2]

State the names of the parts in Fig. 1 that: 

• produce ovules
• protect the bud of the flower

On Fig. 1, draw an arrow to represent the transfer of pollen from flower K to flower L during pollination.

A student said, “Flowers K and L are pollinated by insects.”

Describe two structures in flowers K and L that support this statement. 

Use features that are visible in Fig. 1. 

Describe the pathway water takes in a plant, as it moves from the soil to a leaf.

Fig. 1 is a diagram of the human female reproductive system.

Fig. 1

Complete Table 1 by stating the letter from Fig. 1 that identifies the structure where each process occurs.

Table 1

[3]

State the name of the part of the female reproductive system labelled S in Fig. 1.

[1]

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Fig. 2 is a diagram of a human sperm cell.

Fig. 2

Write the formula that would be used to calculate the magnification of the diagram.

[1]

The actual length of the sperm cell in Fig. 2 is 0.055mm.

Convert this value to micrometres (μm).

Space for working.

___________ µm  [1]

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Explain why the nuclei of sperm cells differ from those of other cells in the male.

Explain the roles of the flagellum, the mitochondria and the acrosome in sperm cells.

Explain why the sex of a child is determined by its father.

Fig. 1 is a half-flower drawing of pride of Barbados, Caesalpinia pulcherrima.

Fig. 1

Complete Table 1 by stating the letter from Fig. 1 that indicates the organ where each function occurs and the name of the organ.

Table 1

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Fig. 2 is a scanning electron micrograph of some pollen grains from wind-pollinated flowers and insect-pollinated flowers.

Fig. 2

Write the formula that would be used to calculate the actual diameter of pollen grain H.

[1]

The actual diameter of pollen grain H is 0.082mm.

Convert this value to micrometres (μm).

Explain how the pollen grain labelled J is adapted for insect pollination.

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Pollen grains grow tubes, which contain haploid male gamete nuclei.

One of these male gamete nuclei fuses with the female gamete. State the part of the flower that contains the female gamete

[1]

Define the term haploid nucleus.

Explain why it is important for gametes to be haploid.

State one type of blood cell that is involved in the defence against disease.

[1]

State two ways blood cells defend the body against disease.

HIV is a sexually transmitted infection (STI).

Define the term sexually transmitted infection.

[2]

Explain how the spread of STIs can be controlled.

[3]

Glycogen is a storage carbohydrate in animals. Glycogen is made from glucose.

[2]

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A fetus needs glucose to make glycogen. 

Describe how a fetus obtains glucose.

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Fig. 1 shows the concentration of glycogen in the fetus of a domestic cat during pregnancy and immediately after birth.

Fig. 1

Hormones stimulate changes in the concentration of glycogen in the fetus.

Define the term hormone.

[3]

Calculate the percentage increase in the glycogen concentration in the fetus between day 10 and birth in Fig. 1.

Give your answer to the nearest whole number.

Show your working.

Describe the changes in glycogen concentration shown in Fig. 1 and explain how hormones in the fetus cause these changes.

Use data from Fig. 1 to support your answer.

[6]

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After birth, cats produce milk to feed their offspring.

Human babies can be breast-fed or bottle-fed with formula milk.

Outline three disadvantages of breast-feeding.