This document provides an overview of plant cell structures, the processes of pollination and fertilization, and fruit classification. It defines pollination and fertilization, describes the parts of the flower involved in each process, and explains how wind and insect pollination differ. The summary also outlines double fertilization in flowering plants and how it leads to the formation of seeds within fruits. Different types of fruits are classified based on their structure and development.

1. RHS Level 2 Certificate
Review of cells, pollination and
fertilization and fruits

2. Learning outcomes
• Identify and describe the different parts of the
plant cell
• Describe the processes of wind and insect
pollination
• Define pollination
• Define fertilization
• Describe the process of fertilization
• Classify various types of fruit

3. Plant Cells
• Cell Wall – made of cellulose, holes allow plasmodesmata
(cytoplasm) out to connect the cells to each other chemically
• Cell membrane – surrounds the living content of the cell;
inside the cell wall.
• Cytoplasm – the living content of the cell
• Nucleus – contains chromosomes that are strands of DNA
• Vacuole – sac containing dilute sugars and nutrients and
waste products.
• Chloroplast – contains chlorophyll, site of photosynthesis
• Mitochondria – site of respiration, releases energy from
carbohydrate

4. Cell diagram

5. Structure of a typical insect pollinated flower

6. Structure of a typical wind pollinated flower

7. Pollination
• The transfer of pollen from the anther (where it
is made) to the stigma.
• Cross pollination: pollen transferred to a
different individual of same species
• Self pollination: pollen transferred to the
stigmas of the same flower (hermaphrodite
flower) or to a female flower on the same plant
(monoecious)

8. Pollination
• Agents have to be used
to transfer pollen
• Animals: insects, birds,
bats mice etc….
• Wind
• Water currents

9. Wind Pollination
• Flowers have no need
to attract insect
• Stigma and stamen
usually small and on
long stalks to catch the
wind
• Huge quantities of tiny
light coloured pollen
grains produced

10. Wind Pollination
• They are the usual
cause of hay fever!
• Wind pollen is usually
small and light
• Often contains air sacs
• Grasses and many
trees are wind
pollinated

11. Insect Pollination
• Insect pollen is often sticky!
• Nectar rewards the insect
• Pollen often contains
carbohydrates as food for
the insect
• Flowers have ultra-violet
sensitive pigments that
direct the insects to the
stamen and pistil

12. Fertilization takes place within the
flower.
• Male gametophytes, or pollen grains, are produced in the
anthers.
– Haploid male gametes
produced in anthers
by meiosis
– each gamete divides by
mitosis to form two
identical haploid cells •pollen grain
– two cells form a
single pollen grain

13. • One female gametophyte can form in each ovule of a flower’s
ovary.
– Haploid female gametes produced in ovule by
meiosis
– one gamete develops into female gametophyte
– female gametophyte contains a number of cells
– one cell has two nuclei, or polar nuclei (one set of
chromosomes each – a double haploid)
– one haploid cell will develop into an egg

14. • Pollination occurs when a pollen grain lands on a
stigma.
– The pollen must be compatible to fertilize the ovum – that
means that the pollen must ‘recognise’ the chemical signature
of the stigma
– If the pollen is compatible it is stimulated to divide by the
chemicals produced by the stigma. If not compatible it will
die.
– one cell from pollen grain forms pollen tube
– other cell forms two sperm that travel down tube

15. • Flowering plants go through the process of
double fertilization.
•female
•gametophyte Pollen tube
•egg
•sperm
•polar nuclei
•ovule

16. • Flowering plants go through the process of double fertilization.
•endosperm
– one sperm fertilizes
the egg and forms a •seed coat
diploid zygote which
has DNA from both
parents
– other sperm unites
with polar nuclei,
forming endosperm
– endosperm provides •embryo
food supply for embryo

17. • Each ovule becomes a seed.
• The surrounding ovary grows into a fruit.

18. Fruits
• The part of the reproductive structure surrounding
the seeds, e.g. pods and nuts as well as the fruits
that we eat.
• Develops from the ovary; if the structure around the
seeds develops from other parts of the flower it is a
‘false fruit’
• Parthenocarpy is the formation of fruit without
fertilization
• Classification of fruit – a number of systems and no
botanical agreement.

19. Classification of Fruit – simple scheme
• Simple fruit – formed from one ovary, may contain one or
many seeds. E.g. Prunus x domestica
• Aggregate fruit – formed from the fusion of many ovaries in
one flower. E.g. Raspberry Rubus ideaus
• Compound fruit – Formed from the ovaries of several grouped
flowers e.g. Pineapple Ananus comosus
• Dehiscent – splits open to release seeds e.g. Lathyrus
odoratus pod
• Indehiescent – does not split open e.g. Quercus robur acorn
• Berry – a simple fruit with no hard layer of endocarp around
the seeds e.g. Lycopersicon esculentum
• Drupe – a simple fruit with a stony layer of endocarp around
the seed e.g. Prunus x domestica