Kingdom Plants.

Bryophytes (Mosses)

h  Mosses are simple land plants.

h  Each plant has a slender stem with numerous small leaves arising from it.  

h  Every leaf does not have specialised cells.

h  The inner most cells conduct water and food.

h  There are no proper roots, but there are rhizoids which are like multicellular root hairs.

h  Mosses reproduce sexually but do not form seeds.  The male and female gametes fuse at the tip of a moss plant to produce a spore capsule on the end of a long stalk.  The spore capsule opens to release single celled spores which are scattered and grow into new moss plants.

The Ferns

v                 Ferns are land plants, much larger than bryophytes and more highly developed.

v                 They are common in damp places of the woods, ravines and rocky crevices.  Only deserts and the polar regions have no ferns.

v                 Ferns are non-flowering plants that grow from spores instead of from seeds.

v                 Their stems, leaves and roots are very similar to those of the flowering plants.

v                 The leaves are called fronds.

v                 Fronds have a single midrib, with small leaflets branching off from either side.

v                 On the underside of a fertile frond are clusters of brown dots.   The dots are called sori (singular sorus).  These are made up of many spore cases called sporangia.

v                 The stem takes the form of a rhizome.

v                 The stem and leaves have sieve tubes and water conducting cells similar to those in the xylem and phloem and flowering plants.

v                 Ferns also have multicellular roots with vascular tissue.

Differences between Conifers (Gymnosperms) and Flowering Plants (Angiosperms)

Phylum Angiosperms:  Flowering Plants.

This phylum includes plants that have seeds formed within the ovaries of flowers and not naked like in the previous phylum conifers.  There are two main groups:  the moncots and the dicots.

Differences between Dicotyledons and Monocotyledons.

Sepals - are small and leaf like, usually found below the petals when the flower is open and when the flower is closed, they are the “pocket” in which the petals are closed.

Petals - large, usually colourful and scented to attract the insects for pollination.

Stamens - male part of the flower, produce pollen grains. Each pollen grain contains a male gamete.  Each stamen has a stalk called the filament, with an anther on the end.

Carpel - female part of flower, contains one or more egg cells called ovaries.  The ovary itself has a tube like structure called the style and a stigma.

Receptacles - The flower structures are all attached to the expanded end of a flower stalk.  This is called the receptacle.

“GCSE Biology” pg. 70.

Flowers of different species vary in the following ways:

1.      The number of sepals, petals, stamens and carpels. 

2.      The number of ovules in a carpel.

3.      The structures may be joined or fused together to varying extents.

4.      The flower may be radically symmetrical or bilaterally symmetrical.

Flowers may be single (solitary) or numerous.  When numerous, the flowers together constitute an inflorescence.  Within an inflorescence the flowers may be arranged in various different ways, depending on the species.

Refer to “GCSE Biology” by Mackean pg. 67-78

Refer to “Biology for Life” by Roberts pg. 368 – 383.

Pollination is the transferring of pollen grains from an anther to a stigma.  There are two types of pollination.

 Self-pollination                                               Cross-pollination

Self-pollination - pollen grains transferred to a stigma in the same flower or to a stigma in another flower on the same plant.

Cross-pollination - pollen grains transferred to a stigma in a flower on a different plant.

Cross-pollination is preferable to self pollination because it creates variety in the species.  Most plants have features which favour cross pollination, and / or reduce the chance of self-pollination.

In cross-pollination the pollen grains are carried by wind or by small animals, usually insects.  Flowers are adapted for one or other type of pollination.

*1*            A pollen tube grows out of the pollen grain.

*2*          The pollen tube grows into the stigma and down the style to the ovary.

*3*          The pollen tube grows into the ovule (usually through the micropyle) and releases a male nucleus into the embryo sac.

*4*          The male nucleus fuses with the egg cell (fertilisation), thus forming a fertilised egg (zygote).

1.      The zygote develops into an embryo.

2.      The embryo becomes surrounded by endosperm tissue which nourishes it.

3.      The ovule develops into the seed, the wall of the ovule becomes the seed coat.

4.      The ovary develops into the fruit.

5.      The seed dries out, becoming dormant.

6.      The sepals, petals, and stamens wither away and drop off.

The cotyledons store food (starch) for use when the seed germinates.  Some seeds contain endosperm tissue which provides food when the seed germinates.  Such seeds tend to have small cotyledons.

Seeds of different species vary in the following main ways:

·         size and shape (related to the method of dispersal)

·         number of cotyledons (dicotyledons have two cotyledons, monocotyledons have one).

·         the size of the cotyledon(s).

·         the presence or absence of endosperm tissue.

C     By wind and air currents

C     By animals and insects

C     By water

C     By being eaten - fleshy fruits are eaten by birds and seeds pass out unharmed with faeces.

C     By an explosive mechanism - spore or seed case may split open violently, throwing contents over  a wide area, e.g. spores of fern, seeds of pea and bean plants and wallflower.

C     By a pepper pot mechanism - open spore or seed case may be shaken by the wind, scattering contents e.g. seeds of poppy.

Refer to “GCSE Biology” by Mackean pg. 73 figure 8.15

Refer to pg 378 of “Biology for Life” by Roberts.

Germination.

• The epicotyl is the part of the plant embryo ABOVE the cotyledon & becomes the stem
• The radicle is the part of the plant embryo BELOW the cotyledon & becomes the root
• The hypocotyl is the part of the plant embryo BETWEEN the cotyledon &  the radicle
• The hilium is a scar along the seed edge where it was attached to the ovary
• In monocot seeds like corn, a sheath called the coleoptile grows out of the ground to protect the newly emerging plant

• Many seeds require environmental factors, such as Water, Oxygen, and Temperature to trigger germination
• Some seeds only germinate after exposure to extreme cold or after passing through an animal's digestive tract
• Water must FIRST be absorbed by the seed to break the seed coat & activate enzymes to change starch in the endosperm or cotyledons into simple sugars for energy
• The radicle emerges first

• Once the seed coat opens, OXYGEN is needed for cellular respiration carried on by the embryo plant
• The shoot (hypocotyl & embryonic leaves) begin to grow, synthesize chlorophyll, and carry on photosynthesis

• After the stored food is used up in dicots, the cotyledons fall off

Dicot Seed Germination

• In Monocots like corn, the Cotyledon remains underground and transfers nutrients to the growing Embryo.

1. In your own words explain what is vegetative propagation / reproduction.
2. What is a stolon?
3. What is the difference between a stolon and a rhizome?
4. What is a bulb?
5. What is the difference between a bulb and a corm?
6. Potatoes are stem tubers.  What is the main purpose of the tuber?
7. How can a tuber be a means of reproduction?
8. Mention 3 advantages of vegetative reproduction.
9. Do you think that there are disadvantages?  Mention some.
10. What are clones?
11. In case of clones, would it be an advantage if the crop has bad characteristics?
12. Mention 2 types of artificial propagation.
13. 1a.  Draw and label the structure of a flower showing its reproductive organs.
14. 1b.  Explain what is the stamen and what it includes.
15. 1c.  Explain what is the carpel and what it includes.
16. 2a.  What is pollination, and what are the two types of pollination?
17. 2b.  Which one creates variety in the species?
18. State 3 differences between wind-pollinated flowers and insect-pollinated flowers.
19. Explain what happens during fertilisation by writing down the steps.
20. What happens after fertilisation?
21. Label this diagram of a longitudinal section through an apple.

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