The first plants evolved from freshwater algae which transitioned from living in water to land approximately 500 million years ago. Advantages the plants got from living on land instead of water are: more sunlight, more resources, speeding up of photosynthesis, adaptation development and advantageous food chains.

Plants also evolved before humans as they could turn CO2 into oxygen which helped us evolve. Sadly, 21% of the 400,000 species of plants are at risk of extinction.

Plants are alive because they can follow MRS GREN.

They follow movement as plants can move by growing towards different stimuli (eg. light and water). Examples of this are: sunflowers face the sun throughout the day.

They follow respiration - release of energy - as they respire all the time because they need to release energy from glucose made in photosynthesis. This is so important as plants die without respiration.

They follow sensitivity as shoots grow and bend towards light by osmosis, so that leaves can photosynthesize.

They follow growth as plants mainly grow at the tips of their roots and shoots and they can grow throughout their life as long as their conditions are correct.

They follow reproduction as most plants reproduce sexually with pollen and eggs. Some also use asexual reproduction by making flowers.

They follow excretion - removal of waste - as plants excrete oxygen to give us life and at night they excrete CO2 to fight for our oxygen. They are excreted through pores in the leaf called stomata in photosynthesis.

They follow nutrition as plants make their own food (glucose) by photosynthesis. They also absorb mineral ions from the soil to build proteins and liquids.

Lesson 2: Plant phyla (Key skill 2)

Classification:

Classification refers to how biologists try to group organisms based on evolution.
Every plant can be classified into one large group known as the plant kingdom.
The 4 big plant subdivisions are called phyla.

The four phyla are:

Bryophytes - mosses, liverworts and hornworts - approximately 23,000 species.

Ferns - filincopyta - approximately 15,000 species.

Gymnosperms - conifers - approximately 1,000 species

Angiosperms - flowering plants - approximately 350,000 species.

Classification of Plants | 4 Main Types of Plants | BioExplorer

IMPORTANT: The word ‘sperm’ inside a plant phyla (angioSPERMs, gymnoSPERMs) means that they ‘grow with seeds’! So, angiosperms and gymnosperms grow with seeds and also reproduce with pollination.

Bryophytes - mosses and liverworts - have long and thin leaves with no stem, they live in wet and damp environments as they are required for no roots and stem. Their overall shape is usually blobby and springy. They grow with spores not seeds and they grow on something solid like rocks and trees.

Ferns have many leaves joined to make a big leaf; similar to a Christmas tree. Ferns have stems and do not produce flowers. They have spores and they use them to reproduce, so they have no seeds. They have leaves, roots and stems and their leaves are pinnate - leaves arranged on either side of the stem, typically in pairs opposite each other. The little circles on the stems are the spores.

Gymnosperms - conifers - “naked seeds” - They have needle shaped leaves which is an adaptation. They have leaves and their shape is quite long and spiky. This is advantageous to scare off predators. They have woody stems and they do not flower. The purpose of the pine cone is to help pollination and reproduction. Pine cones have seeds inside and grow with seeds. They also have leaves roots AND stems. Their adaptation is when it is cold and wet the pine cones close and when it is hot and dry the pine cones open for seed dispersal.

Angiosperms - flowering plants - They produce flowers because they are easy to pollinate and they have brightly coloured petals to attract insects as they are easy to spot. Not all angiosperms are brightly coloured as some pollinators could be colourblind so other attractions are used, like smell. They have stems, leaves, roots, petals, sepals, carpel and stamen.

Summary:

Bryophytes

Structures:
- Long and thin leaves
- No stems
Characteristics:
- Blobby and springy shape
- Thrives in wet and damp environments
- Grows on solid surfaces (e.g., rocks, trees)
Reproduction: Spores

Ferns

Structures:
- Pinnate leaves
- Stems
- Roots
Characteristics:
- Large leaves resembling a Christmas tree
- No flowers
- Spores located on stems
Reproduction: Spores

Gymnosperms

Structures:
- Needle-shaped leaves
- Woody stems
- Pine cones
Characteristics:
- Long and spiky shape to deter predators
- Adapted for cold and wet conditions
Reproduction: Seeds

Angiosperms

Structures:
- Flowers
- Stems
- Leaves
- Roots
- Petals
- Sepals
- Carpel
- Stamen
Characteristics:
- Brightly coloured petals to attract pollinators
- Various mechanisms for attracting different pollinators
Reproduction: Seeds

Lesson 3: Angiosperms (Key skill 3)

Angiosperms all produce flowers: flowers are reproductive organs that allow angiosperms to reproduce sexually.

Like animals, plants produce sperm and egg cells - but unlike animals, plants cannot move around to choose a mate. The purpose of a flower is to provide a place where sperm cells and egg cells can meet and produce a seed containing a new plant embryo.

This is a diagram of an angiosperm:

Carpels are always in the middle and stamens are to the side unless there are adaptations or wind pollination.

Flowers have both gender parts at times but they do not ripen at the same time because they can fertilize due to that. Fertilise meaning reproduce.

The collective name for the female parts - stigma, style, ovary, ovules - is the carpel and the collective name for the male parts - anthers, filaments - is the stamen.

KEY INFO:

Sepals are located just outside the petals and its function is to protect the flower bud before it blooms and support the petals after blooming/

Petals are located at the outer base of the flower, they are quite large and usually brightly coloured to attract insects because there is nectar inside. But, sometimes petals are not brightly coloured as some animals are colourblind, so they may use scent to attract animals instead. Sometimes, the petals are also fused with the sepals.

The carpel which is the name of the collective female parts of a flower, is located at the centre of the flower. It is usually in the centre of a flower unless there is an adaptation and it contains the stigma, style, ovary and ovules. The stigma is at the top of the carpel and it is where pollen grains stick to in pollination. The ovary is at the bottom of the carpel and it is the reproductive organ that produces and holds ovules (eggs). The ovules are always inside the ovaries. Then, you have the style which is a tube that support the stigma and links it to the ovary. The stigma is usually sticky so that more pollen grains can stick there during pollination.

The stamen which is the name of the collective male parts of a flower, is located to the sides of the carpel; the carpel is usually in the centre of an angiosperm unless there is an adaptation. The stamen contains the anther at the top which produces pollen for pollination and is covered in pollen and the filament supports the anther.

Lesson 4/5: Pollination (Key skill 4/5/6)

Pollination happens in angiosperms and gymnosperms as they both move sperm cells by producing a powder of microscopic grains called pollen. Each pollen grain contains a small number of cells that can produce sperm and reproduce.

Pollen grains are produced by the anthers on the filaments in the stamen and they are received at the stigma of the carpel.

The definition of pollination is: The transfer of pollen from an anther to a stigma leading into the carpel.

There are two types of pollination:

Animal pollination
Wind pollination

In animal pollination, there are two more types of pollination: cross and self pollination.

Cross-pollination is the transfer of pollen from the anther of one plant and to the stigma of another.

Self-pollination is the transfer of pollen from the same plant anther to the same plant stigma OR the same plant’s flower anther to the same plant’s different glower stigma even if it moved to different plants because it is the same plant’s flower it still counts as self-pollination.

Self-pollination with the same plant is possible because most plants have both male and female parts on the same flower, this type of flower is called hermaphroditic. But, in some plant species there are separate male and female flowers.

Anthers and filaments are present in male flowers and stigmas, styles, ovaries and ovules are present in female flowers. In hermaphroditic flowers it contains all: stigmas, styles, ovaries, ovules, anthers and filaments.

The different offspring of plants produced by cross pollination and self pollination are different as cross pollination causes variation and pollination does not because during cross pollination there are two different parents as two different types of plants involved compared to self-pollination which is either on the same flower or plant which causes no variation as it is the same parent.

Wind pollinated plants rely on wind to carry their pollen grains therefore leading to lightweight pollen grains and a bigger stigma to catch the pollen grains. Wind pollinated plants are usually small and have no nectar and scent but they have a specific shape. Wind pollinated plants are also the reason human allergies can be triggered.

Bee and butterfly pollinated plants have bright colours to attract them, strong scent, have a specific shape to implement a landing pad and those plants also produce nectar.

Bird pollinated plants have bright colours, no strong scent and produces nectar, and it has a special tube shape for birds to stick their beak in.

Fly pollinated plants are a different story; they have dull coloured petals such as dark brown and dark purple, they have a strong rotten meat scent, they are funnel shaped and do not produce nectar.

Bat pollinated plants do not have bright colours as they are blind, they do have strong odours, a specific shape to stick their head in and produces nectar.

A sticky stigma is a feature of many plants to help catch pollen grains more effectively helping the transportation of pollen.

Lesson 5: Seeds + what happens when pollen arrives at the stigma? (Key skill 7/8)

When the pollen arrives at the stigma, it produces a pollen tube that grows down the stye to reach the ovaries, which contain the ovules - egg cells.

Two pollen cells containing sperm travel down the pollen tube and one of these will fuse with an egg in the ovaries to produce a new plant embryo - unhatched offspring. This is called fertilization.

This image shows the sperm going down the pollen tube: After what happens in the image a sperm cell fuses with an egg cell making a new plant embryo - fertilization,

What happens as the plant embryo grows?

Before the new plant embryo is released by the plant, it is encased in a protective covering a seed which contains an embryonic (baby) shoot - plumule, an embryonic (undeveloped) root (radicle), a cotyledon (embryonic leaf) which are specialised seed leaves that stores food for the embryo and around it like a cell wall if the seed was a cell, a seed coat called a testa which protects the embryo from physical damage - squashed, predators and/or drying out.

Wind and water pollinated plants have different sizes, structures and weights so that the wind and water can transport it easier as those plants rely on wind and water to move pollen grains.

It is advantageous for plants to produce seeds rather than releasing the plant embryo unprotected because:

The embryo can be vulnerable to drying out, physical damage and predators so it needs to be protected
The seed provides food for the embryo

Some people get confused between pollination and seed dispersal as they can both occur by wind and animals but some animals pollinate but do not disperse seeds (ie bees) and vice-versa.

Seed dispersal is the process by which seeds are spread from the parent plant to new locations.

Seed dispersal can happen via animals or wind and water too; of course, the seeds produced by animal dispersed plants and wind and water dispersed plants will be different as wind and water dispersed plants may have different structures and be more lightweight to have more effective dispersion. Some seeds can be dispersed by touch, of predators, humans, rain and animals, such as the squirting cucumber. These plants explode their seeds when touch is felt with power which can disperse them into wide ranges of areas.

It is beneficial for seeds to be dispersed far away from the parent plant instead of in the same place because:

If they are not all spread out there is a high amount of competition for sunlight and water; plants make their own food (glucose) by photosynthesis. NOTE: NO USING THE WORD NUTRIENTS IN BIOLOGY
Plants also need space to grow, therefore the further you go, the more space there is.
Plants also need genetic variation too, the more space a plant covers, the more chance it can get pollinated or produce pollen for another plant to be pollinated, creating two parents for the new plant.

Bear in mind that these seeds can germinate (grow into seedlings) too!

There is a wide variety of seed shapes and structures so that different seed dispersal methods can be met, here are some different times of seed dispersal methods that are used by plants:

Some seeds are given to animals to eat and excretes those seeds into areas with more resources letting that seed grow.
Poppies use wind seed dispersal, therefore their seeds are more light and have to fly quicker. When it feels the time is right, holes appear as the seed capsule dries and the seeds fly out and the wind helps it disperse into different areas.
Conifers - gymnosperms - use wind and animal eating as female cones protect the seeds by closing their scales when it is cold and wet, but when it is hot and dry the scales open letting the seeds disperse; that is an adaptation that they have.
Sycamores use wind dispersal as they seeds have “wings” attached so when they are pushed by the wind they can fly further.
Thistles are wind dispersed as the seeds are connected with a feather like parachute called pappus to fly further helped by the wind.

Remember to underline scientific names of organisms as they are in Latin!

Lesson 6/7: Photosynthesis (Key skill 9/10)

KEY WORDS:

Bryophytes:
One of the four plant phyla that contain: mosses, liverworts, and hornworts that have long and thin leaves with no stem and reproduce with spores.

Ferns:
One of the four plant phyla that have plants with many leaves joined to make a large leaf, they have stems, roots, and reproduce with spores.

Gymnosperms:
One of the four plant phyla that contain conifers with needle-shaped leaves, woody stems and they reproduce with seeds and pollination.

Angiosperms:
One of the four plant phyla containing flowering plants that produce flowers that reproduce with seeds and pollination.

Petals:
Large and usually brightly coloured parts of a flower that attract insects because they contain nectar.

Sepals:
Parts located just outside the petals that protect the flower bud before it blooms and support the petals after blooming.

Stigma:
The top part of the carpel where pollen grains stick to during pollination.

Style:
The tube that supports the stigma and links it to the ovary.

Ovary:
The reproductive organ at the bottom of the carpel that produces and holds ovules (eggs).

Ovules:
Egg cells contained within the ovary that develop into seeds after fertilization.

Anther:
The part of the stamen that produces pollen for pollination.

Filament:
The part of the stamen that supports the anther.

Stamen:
The male parts of a flower, consisting of the anther and filament.

Carpel:
The collective name for the female parts of a flower, including the stigma, style, ovary, and ovules.

Pollen:
Microscopic grains produced by the anthers that contain sperm cells for reproduction.

Hermaphrodites; hermaphroditic:
Flowers that have both male and female parts, allowing for self-pollination.

Cross-pollination:
The transfer of pollen from the anther of one plant to the stigma of another plant.

Self-pollination:
The transfer of pollen from the anther of the same plant to the stigma of the same plant or from the same plant’s flower anther to a different flower’s stigma on the same plant.

Photosynthesis:

Heterotrophic:

Autotrophic:

Chloroplasts:

Chlorophyll:

Note