[BIO] Chapter 15 - Reproduction in Plants

© Hee Xin Wei (Copyrighted) Topic 1 5: Reproduction in Plants

Chapter Analysis FOCUS EXAM WEIGHTAGE •Constitute to around 0.5% in Paper 2 in the past 5 years •commonly tested in MCQ •straightforward chapter

flower structures pollination fertilisation Key Concept

reproduction •Reproduction is the biological process by which new organisms are produced to ensure the perpetuation of the species. •Two type of reproduction: 1.Asexual reproduction is the process of producing a genetically identical offspring from one parent without the fusion of gametes. asexual reproduction Advantages Disadvantages Asexual reproduction -Only one parent required as fusion of gametes is not required. -All beneficial qualities are passed onto the offspring. -Faster method of producing offspring as compared with sexual reproduction. -Since organisms are already in a suitable habitat, they can colonise the area rapidly. -No genetic variation in the offspring. Hence, species are may be wiped out if not well adapted to changes in the environment.

Reproduction sexual reproduction Advantages Disadvantages Sexual reproduction -Offspring may inherit beneficial qualities from both parents. -There is greater genetic variation in the offspring, thus species can be better adapted to changes in the environment. -Two parents are required (except in plants with bisexual flowers) as fusion of gametes is required -Slower method of producing offspring as compared to asexual reproduction 2.Sexual reproduction is the process involving the fusion of gametes, one from each parents, to form a zygote during fertilisation. The outcome is genetically dissimilar offspring.

structure of a flower plant Pedicle Carpels Sepal •Modified leaves which are found on the outermost ring of floral leaves. •They enclose and protect the flower when it is in bud stage. Petal •Modified leaves which form the most conspicuous part of the flower. -They are large and brightly coloured in insect-pollinated plants -Form a platform for insects to land on. Anther •Male reproductive organs in plants •The anther consists of two lobes and a vascular bundle •Each lobe contains two pollen sacs, which contain pollen grains (male gametes) Filament Stalk that holds the anther in a suitable position to disperse pollen Carpels •Female reproductive organ in plants. •Stigma: Receptor of pollen grains. Secretes a sugary fluid that stimulates germination of pollen grains. •Style: Holds the stigma in position to trap pollen grains. •Ovary: Each ovary contains one or more ovules, which contains female gametes structure of a typical insect-pollinated flower

Pollination self pollination Advantages Disadvantages Not dependent on external agents of pollination such as insects or wind There is less genetic variation, hence the offspring is less adapted to environmental changes. (this is NOT the same as asexual reproduction. There is fusion of gamete thus offspring is NO