Reproduction in Plants: Answers

Give three difference between sexual and asexual reproduction.

1. Sexual reproduction involves two parent whereas asexual reproduction only involves one.

2. Sexual reproduction involves cell division by meiosis whereas asexual reproduction involves cell division by mitosis.

3. Sexual reproduction produces offspring which are genetically different to the parents whereas asexual reproduction produces offspring which are genetically identical (clones).

State three ways in which the structure of insect-pollinated flowers differs from the structure of wind-pollinated flowers.

1. Insect-pollinated flowers have large, brightly coloured petals which are absent in wind-pollinated flowers.

2. Their stigma and anthers are enclosed and shielded by the petals. The stigma and stamen is much smaller in insect-pollinated flowers. In wind-pollinated flowers, the stigma is very big and has a feathery shape.

3. Insect-pollinated flowers have a nectary to produce nectar - this is absent in wind-pollinated flowers.

A bee covered in pollen lands on the stigma of an insect-pollinated flower. Describe the events which lead to seed formation.

When the pollen tube attaches to the stigma, a pollen tube forms down the style towards the ovary. The pollen is then able to travel through the tube to reach the egg (ovule) in the ovary. It enters the ovule through the micropyle and the nucleus of the pollen grain and the nucleus of the ovule fuse in the process of fertilisation. After fertilisation, the ovule becomes the seed and the ovary becomes the fruit.

Describe the features of an insect-pollinated flower that help it to attract insects.

Insect-pollinated flowers have big, brightly coloured petals and sweet-smelling nectar which help it to attract insects.

Describe a method a gardener would use to produce a clone of a particular plant.

A common gardening technique involves taking cuttings of the plant you’d like to clone. A short-section or side-branch is taken from the plant and its end is dipped in rooting powder. The rooting powder contains nutrients and plant hormones which encourage new roots to grow. The cutting is kept in warm, moist conditions and planted when new roots appear. Another artificial cloning method is micro-propagation (tissue culture), but this is a much too complicated method for the average gardener and would usually be carried out in specialised facilities.

Give an advantage and a disadvantage of asexual reproduction.

An advantage of asexual reproduction is that it replicates any desirable characteristics in the original plant. Let’s say that I have grown some particularly tasty tomatoes, I could use cloning methods to ensure the next generation of tomatoes are just as tasty. A disadvantage of asexual reproduction is that there is a lack of genetic variation in the offspring, making them equally susceptible to environmental changes or disease.