Control and coordination in plants

One example of chemical control and co-ordination in plants is the breakdown of stored food reserves during the germination of cereal grains such as wheat.

Feb/March 2017

Section B. Select one question and answer it.

Feb/March 2018

Many processes and activities in plants and animals arise from ions moving. Table 5.1 shows several ions, the direction each ion moves in and the effect produced by that movement. Complete Table 5.1 by filling in the missing details.

Feb/March 2021

Fig. 10.1 illustrates the arrangement of two guard cells.

Feb/March 2022

An experiment was done to find out how different blue-light intensities affect the percentage germination of barley seeds. The barley seeds were exposed to blue light for seven days. All other variables were kept the same. The findings are given in Table 9.1. The influence of blue light on the concentration of abscisic acid (ABA) was also examined. ABA concentration was recorded at intervals across seven days in barley seeds exposed to blue light with an intensity of 57 arbitrary units. The findings are given in Table 9.2. For comparison, in the dark the concentration of ABA in barley seeds decreased from $100\ \text{au}$ at the start (day 0) to $45\ \text{au}$ on day 1 and then stayed unchanged from day 1 to day 7.

Feb/March 2024

Describe how abscisic acid (ABA) is involved in the closure of a stoma.

May/June 2011

Describe the role of abscisic acid (ABA) in bringing about stoma closure.

May/June 2011

Fig. 8.1 presents a diagram of a stoma together with its guard cells and the neighbouring epidermal cells.

May/June 2012

Fig. 1.1 illustrates part of a cell from a plant’s growing region.

May/June 2019

Gibberellin is a plant hormone that plays an important part in seed germination. Fig. 6.1 shows a diagram of a section through a barley seed (grain).

May/June 2022

Stomata in leaves react to environmental changes by opening and shutting. This controls the uptake of carbon dioxide and the loss of water.

May/June 2024

Where gibberellins are present in a plant cell, genes associated with stem elongation are switched on.

May/June 2025

An investigation was done into how the plant growth regulator auxin affects apical dominance. The apical buds of 20 pea plants were removed and thrown away. The cut surfaces of 10 pea plants were covered with an inert paste containing auxin. The cut surfaces of the remaining 10 pea plants were covered with inert paste only. Another group of 10 pea plants had their apical buds left intact and were not covered with paste. This group acted as a control. The lengths of the side shoots on each of the three groups were measured at regular time intervals and mean values were worked out. The results are shown in Fig. 7.1.

Oct/Nov 2010

An experiment was conducted to investigate the effect of the plant growth regulator auxin on apical dominance. • The apical buds of 20 pea plants were removed and thrown away. • For 10 pea plants, the cut ends were covered with inert paste that contained auxin. • The cut ends of the remaining 10 pea plants were covered only with the inert paste. • Another 10 pea plants kept their apical buds intact and were not given paste. This served as the control group. The lengths of the side shoots in each of the three groups were recorded at fixed time intervals, and mean values were then worked out. The results are shown in Fig. 7.1.

Oct/Nov 2010

Cultivated rice, Oryza sativa, is commonly grown in waterlogged fields.

Oct/Nov 2011

The passage below outlines the effects of gibberellins on seed germination. Complete the passage by inserting the most suitable scientific term(s).

Oct/Nov 2013

The passage below outlines how auxin affects shoot growth.

Oct/Nov 2013

Section B. Select one question to answer.

Oct/Nov 2014

Section B. Answer just one question.

Oct/Nov 2014

Explain the function of auxin in plant cell elongation.

Oct/Nov 2016

Explain how auxin contributes to cell elongation in plants.

Oct/Nov 2016

Describe the Venus fly trap’s response when it is touched.

Oct/Nov 2016

Gibberellin is a plant growth hormone with a part to play in germination and stem elongation.

Oct/Nov 2018

The Venus fly trap, Dionaea muscipula, is a carnivorous plant that is native to wetlands on the East Coast of the USA. In these wetlands, mineral ions from dead and decaying organisms are often washed out. Fig. 7.1 shows a Venus fly trap leaf.

Oct/Nov 2019

The Venus fly trap, Dionaea muscipula, is a carnivorous plant that is native to wetlands on the East Coast of the USA. In these wetlands, mineral ions released from decaying organisms are often washed out. Fig. 7.1 shows a Venus fly trap leaf.

Oct/Nov 2019

Gibberellin is a plant growth regulator that plays a role in the germination of barley seed. Gibberellin production is triggered by water uptake. State the site of gibberellin synthesis in a barley seed during germination.

Oct/Nov 2021

Explain how dip sticks are used to test a urine sample for glucose.

Oct/Nov 2021

Gibberellin is a plant growth regulator involved in barley seed germination. Its production is stimulated when water is absorbed. State the location where gibberellin is synthesised in a barley seed during germination.

Oct/Nov 2021

Across many plants, leaves contain stomata that open and shut in a regular daily cycle over 24 hours.

Oct/Nov 2024

Many plant leaves contain stomata, and these open and close in a regular 24-hour cycle each day.

Oct/Nov 2024

Rice, Oryza sativa, is a crop species that has become adapted to living in flooded fields. Fig. 1.1 shows the effects of flooded-field growth on rice plants.

Oct/Nov 2025

The Venus fly trap, Dionaea muscipula, is a plant capable of catching insects. Each leaf of a Venus fly trap is changed so that it has 2 lobes. Fig. 7.1 shows the Venus fly trap leaf in a folded (closed) position after an insect has been caught.

Oct/Nov 2025