Biodiversity Revision Notes
Bryophytes:
- Non-vascular plants are the most basal.
- Sister group – ancestral green algae.
Alternation of generations
- Bryophytes have homosporous reproductive strategy with the gametophyte (the dominant phase
of the lifecycle).
1. Seed lands on damp, fertile soil.
2. Develops into a multi-cellular structure – gametophyte.
3. Grows male (antheridium) and female (archegonium) parts.
4. Can only work if it is damp – film of water over it.
5. Antheridium produces sperm that swim across the water and fertilises the female part.
6. Produces a 2n sporophyte.
7. Sporophyte produces a capsule with many cells.
8. Each cell undergoes meiosis to produce spores.
9. Released into the wind as individuals.
10. Blown into a damp bit of soil.
- Alternate between a gametophyte (n haploid) and sporophyte (2n diploid). Alternation of
generations.
- Sporophyte is dependent upon the gametophyte to provide it with resources.
- Sporophyte phase is short-lived.
- Homosporous reproductive strategy: small, same size spores using both male and female parts.
- Dominant phase of life cycles.
- Liverworts hepatophyta/marchantiopsida
- Hornworts anthocerotes/anthocerotopsida
- Mosses bryophyte/bryopsida/musci
Characteristics of living bryophytes
Reproduction
- Homosporous
- The gametophyte is the dominant phase of the lifecycle. The sporophyte is determinate and partly
dependent upon it.
- Sex organs with a single jacket of eggs (egg cells enclosed in a single flask-shaped archegonium).
- Spermatozoid zooidogamous with two whiplash flagella (male gametes swim in a film of water to
the female gametes).
- Embryogeny exoscopic
- Sporophyte produces numerous isospores enclosed in a protective sporopollenin wall.
- Some capable of vegetative propagation of the gametophyte by fragmentation or specialised
gemmae.
- Vegetative propagation: A method of plant propagation by way of separating new plant individuals
that emerge from vegetative parts (e.g. specialised stems, leaves and roots) and allow them to take
root and grow.
- Gemmae: Cell/cluster of cells that separates from the parent plant to form a new organism.
Growth form:
- Generally diminutive – all are small as they lack lignified connective tissue.
- Gametophyte either:
Bryophytes:
- Non-vascular plants are the most basal.
- Sister group – ancestral green algae.
Alternation of generations
- Bryophytes have homosporous reproductive strategy with the gametophyte (the dominant phase
of the lifecycle).
1. Seed lands on damp, fertile soil.
2. Develops into a multi-cellular structure – gametophyte.
3. Grows male (antheridium) and female (archegonium) parts.
4. Can only work if it is damp – film of water over it.
5. Antheridium produces sperm that swim across the water and fertilises the female part.
6. Produces a 2n sporophyte.
7. Sporophyte produces a capsule with many cells.
8. Each cell undergoes meiosis to produce spores.
9. Released into the wind as individuals.
10. Blown into a damp bit of soil.
- Alternate between a gametophyte (n haploid) and sporophyte (2n diploid). Alternation of
generations.
- Sporophyte is dependent upon the gametophyte to provide it with resources.
- Sporophyte phase is short-lived.
- Homosporous reproductive strategy: small, same size spores using both male and female parts.
- Dominant phase of life cycles.
- Liverworts hepatophyta/marchantiopsida
- Hornworts anthocerotes/anthocerotopsida
- Mosses bryophyte/bryopsida/musci
Characteristics of living bryophytes
Reproduction
- Homosporous
- The gametophyte is the dominant phase of the lifecycle. The sporophyte is determinate and partly
dependent upon it.
- Sex organs with a single jacket of eggs (egg cells enclosed in a single flask-shaped archegonium).
- Spermatozoid zooidogamous with two whiplash flagella (male gametes swim in a film of water to
the female gametes).
- Embryogeny exoscopic
- Sporophyte produces numerous isospores enclosed in a protective sporopollenin wall.
- Some capable of vegetative propagation of the gametophyte by fragmentation or specialised
gemmae.
- Vegetative propagation: A method of plant propagation by way of separating new plant individuals
that emerge from vegetative parts (e.g. specialised stems, leaves and roots) and allow them to take
root and grow.
- Gemmae: Cell/cluster of cells that separates from the parent plant to form a new organism.
Growth form:
- Generally diminutive – all are small as they lack lignified connective tissue.
- Gametophyte either:
