Topic 6: Question and Answers

• Answer the questions below.
• Give yourself one hour.
• Check your answers afterwards and do corrections.

Questions

1. How much of South Africa’s land can be used for crop production? (1)
2. Name the five largest contributors towards the gross value of field crops for the past five seasons, and state the contribution of each as a percentage. (10)
3. Give five reasons, apart from their importance to the economy, why plants are important. (5)
4. Indicate whether the following statements are true or false: (15)
   1. In terms of value of production, wheat is the second most important field crop produced in South Africa.
   2. Soya beans contribute about 4,9% to the gross value of field crops.
   3. The South African sugar industry produces an average of approximately 2,2 million tons of sugar per season.
   4. South Africa has one of the largest commercial plantation areas in the world, covering 1,3 million ha.
   5. Stem vegetables require deep soil with a pH range of 5,5 – 7,6.
   6. Leaf vegetables require an average daily temperature of 15 – 20oºC.
   7. Carrots require low temperatures to flower.
   8. Cauliflower is not resistant to frost.
   9. Deciduous fruits require cold, wet conditions during some months of the year.
   10. Apples are a subtropical fruit.
   11. Fynbos requires extremely poor soil and intense fires every 4 – 20 years.
   12. The roots of lucerne fix nitrogen in the root nodules.
   13. Rooibos requires and annual average rainfall of 450–600 mm.
   14. Red clover grows in a wide range of soils, but prefers well-drained loamy soils.
   15. Fodder provides all the nutrients that livestock require.
5. What does the study of agronomy include? (4)
6. List the five categories of vegetable classification and give an example of each. (10)
7. Describe the climatic and soil requirements of bananas. (3)
8. What are the three main types of flower crops grown in South Africa? (3)
9. Name four negative effects alien plants have on the environment. (5)
10. Describe the five ways in which alien plants can be controlled. (10)
11. Name the two categories of fodder and give an example of each. (4)

[Total mark: 70]

Answers

1. 13,5%
2. Maize (48,6%); sugar cane (14,2%); wheat (12,5%); sunflower seed (6,7%); hay (6,0%).
3.                    
   • Oxygen is by-product of photosynthesis.
   • Most of the food that we eat comes from plants.
   • Plants are used as medicines.
   • Plants have aesthetic importance: decoration and aroma.
   • Plants roots reduce runoff and increase the rate of water entry into the soil.
   • The leaf canopy of plants, like trees and shrubs, break the impact of raindrops on the soil surface, and the roots of plants bind the soil to prevent soil erosion.
   • Grasses are used for roofing in the rural areas.
   • Wood is used for sculptural and carpentry designs; for buildings and furniture; gums, paper and rubber.
   • More recently, fuels and gases, like diesel and ethanol, are being made from plants.
   • Plants are a source of fuel in the rural areas (wood for cooking fires).
   • Coal is obtained from decomposed plants. (Any 5)
4.                            
   1. True
   2. True
   3. True
   4. True
   5. False
   6. True
   7. True
   8. False
   9. True
   10. False
   11. True
   12. True
   13. False
   14. True
   15. True
5. Herbaceous field crops / grains, forages, oilseeds, and fibre crops.
6.                          
   1. Root vegetables (e.g. beetroot, carrots)
   2. Leaf vegetables (e.g. cabbage, spinach)
   3. Stem vegetable (e.g. potato)
   4. Fruit vegetables (e.g. tomato)
   5. Flower vegetables (e.g. cauliflower)
7.               
   • Medium to high temperature ranges from 22–35ºC.
   • An even rainfall distribution range of 9–105 mm per month.
   • Rich loamy soil with a lot of organic matter.
8. Fynbos, garden flowers and cut flowers.
9.                        
   • Use scarce water resources
   • Take over most of our arable land
   • Increase bush fires
   • Cause soil erosion
   • Pollute water and affect aquatic life.
10.                                    
    • Mechanical control: removing the invasive plants by physically uprooting them, slashing, mowing, ring-striping or bark-striping them.
    • Chemical control: the application of registered herbicides to the invasive plants or to the soil surrounding them with the aim of killing them.
    • Biological control: the use of host-specific natural enemies to reduce the population of the invasive plant to the barest minimum.
    • Indirect control: the use of other methods that do not directly control the plants, but involves measures like the use of fire, checking entry ports for introduction of alien crops and over sowing beneficial plants at areas infested by alien crops.
11.                          
    • Legume fodder crops, e.g. lucerne or red clover
    • Grass fodder crops, e.g. kikuyu or rye.

[Total marks: 70]