This one is from June 2019, Unit 3101, Taxonomy:
a) Draw a fully labelled diagram to show the structure of a typical legume flower in the space below:
A typical legume flower 5 marks
b) Identify FIVE features of legume flowers which favour pollination. 5 marks
This question relates to the following part of the syllabus:
Outcome 2. Understand the structure and function of plant tissues and organs in the life of the plant.
2.3 Describe plant adaptation for pollination.
Describe how the flowers/inflorescences of named plants are adapted for pollination by different named agents (to include: wind, bee, moth, butterfly, fly, bird), in relation to flower structure/shape, position, colour, scent, provision of food, flowering time, mimicry.
Draw and label diagrams to show the structure of grass and legume flowers and relate to mode of pollination.
State the meaning of cross pollination and self pollination. Explain the benefits of EACH using plant examples.
State the means by which cross pollination is favoured: self incompatibility, flowering time, heterostyly, protandry/protogyny, dioecious plants.
It is a good idea to practice drawing diagrams wherever they are required in the syllabus. Diagrams need to be clear, large and well labelled. Make sure the labels point clearly to the parts intended.
The examiners’ comments state that higher marks were gained ‘where the particular labels gave specific details e.g. keel petal formed of 2 fused petals, 2 wing petals, 1 standard/banner petal, ‘pod’ shaped ovary containing many ovules, 9 fused and 1 free stamen, calyx formed of 5 fused sepals, stigma and style shown protruding’.
For part b) the answers need to directly relate to legume flowers, rather than general pollination, such as a statement that flowers are brightly coloured. Make sure you only include five features as extra ones won’t be awarded any marks.
The examiners’ comments suggest better answers as including:
- Nectar guides drawing bees to nectarines at the base of petals with nectar as a reward
- There may be a sweet scent to attract pollinating insects
- The keel petal acting as a landing pad for bees
- The anther and stigma positioned to rub against the bee
- Pollen with a sculpted exine* to stick to bees
- A description of the mechanism of pollen transfer
(*Exine is the outer coating of a pollen grain - you would not be expected to use this term).