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Some Useful Words For You To Know
Stamen – the pollen producing part of a glower
Style – where the pollen tubes grow
Stigma – a sticky section of the flower where the pollen lands
Sepal – the outer most section of the flower which is usually green and smaller than the petals
Petal – usually the brightly coloured parts of the flower used to attar the insects
Ovary – this protects the ovule and once fertilisation has taken place it will become the fruit
Pullen – minute grains, usually yellow in colour
Reproduction – organisms generate new individuals of the same kind
Germination – when a seed starts to grow
Pollination – transfer of the pollen from the stamen to a stigma
Fertilisation – the combining of cells leading to reproduction
Dispersal – when the seed leaves the flower
Flower Anatomy
Below is a diagram of the anatomy of a flower:
The Flower:
The flower is the reproductive unit of some plants (angiosperms). Parts of the flower include petals, sepals, one or more carpels (the female reproductive organs), and stamens (the male reproductive organs).
The Female Reproductive Organs:
The pistil is the collective term for the carpel(s). Each carpel includes an ovary (where the ovules are produced; ovules are the female reproductive cells, the eggs), a style (a tube on top of the ovary), and a stigma (which receives the pollen during fertilization).
The Male Reproductive Organs:
Stamens are the male reproductive parts of flowers. A stamen consists of an anther (which produces pollen) and a filament. The pollen consists of the male reproductive cells; they fertilize ovules.
Fertilization:
Pollen must fertilize an ovule to produce a viable seed. This process is called pollination, and is often aided by animals like bees, which fly from flower to flower collecting sweet nectar. As they visit flowers, they spread pollen around, depositing it on some stigmas. After a male's pollen grains have landed on the stigma during fertilization, pollen tubes develop within the style, burrowing down to the ovary, where the sperm fertilizes an ovum (an egg cell), in the ovule. After fertilization, the ovule develops into a seed in the ovary.
Types of Flowers:
Some flowers (called perfect flowers) have both male and female reproductive organs; some flowers (called imperfect flowers) have only male reproductive organs or only female reproductive organs. Some plants have both male and female flowers, while other have males on one plant and females on another. Complete flowers have stamens, a pistil, petals, and sepals. Incomplete flowers lack one of these parts.
Pollination
Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (containing the male gametes) to the plant carpel, the structure that contains the ovule (female gamete).
The receptive part of the carpel is called a stigma in the flowers of angiosperms and a micropyle in gymnosperms. The study of pollination brings together many disciplines, such as botany, horticulture, entomology, and ecology. Pollination is important in horticulture because most plant fruits will not develop if the ovules are not fertilized.
The pollen and seeds of flowers can be disperesed by insects and the wind.
Below is a picture of a bee (an insect) collectiing pollen from a flower!!
Below is a picture of dandelion pollinating using the wind.
What Do Plants Need To Grow?
Plants need five things to make them grow:
Light- Water
- Soil
- Warmth
- Air
What Do Seeds Need To Germinate?
Seeds remain dormant or inactive until conditions are right for germination. All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate.
When a seed is exposed to the proper conditions, water and oxygen are taken in through the seed coat. The embryo's cells start to enlarge. Then the seed coat breaks open and a root or radicle emerges first, followed by the shoot or plumule that contains the leaves and stem.
Many things can cause poor germination. Over watering causes the plant to not have enough oxygen. Planting seeds too deeply causes them to use all of their stored energy before reaching the soil surface. Dry conditions mean the plant doesn't have enough moisture to start the germination process and keep it going.
Some seed coats are so hard that water and oxygen cannot get through until the coat breaks down. Soaking or scratching the seeds will help break down the seed coat. Morning glories and locust seeds are examples. Other seeds need to be exposed to proper temperatures. Apple seeds will not germinate unless they are held at cold temperatures for a period of time.
Do All Plants Use Seeds To Germinate?
Non flowering plants like ferns reproduce by "seed-like" structures called spores. Spores are usually found on the undersides of leaves and look like tiny tufts of velvet. Spores are ripe when they easily fall off the leaf. You may want to try to germinate them but it takes a long time for germination and for a plant to develop.
Seed Structure
The outer covering of a seed is called the seed coat. Seed coats help protect the embryo from injury and also from drying out. Seed coats can be thin and soft as in beans or thick and hard as in locust or coconut seeds. Endosperm a temporary food supply, is packed around the embryo in the form of special leaves called cotyledons or seed leaves. These generally are the first parts visible when the seed germinates.
Plants are classified based upon the number of seed leaves (cotyledons) in the seed. Plants such as grasses can be monocots, containing one cotyledon. Dicots are plants that have two cotyledons.
Lets Make A Seed Viewer!
What you will need:
- A clear plastic cup
- Paper towels
- Seeds
- Black construction paper
- Water
Label your viewer- Write your name, the type of seed and the date of planting on the side of the cup
- Make the viewer:
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Line the inside of the cup with black construction paper. Crumple up some paper towels, one at a time, and fill the cup inside the construction paper with them. Cut the top edge of the construction paper so it is even with the top of the cup
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Plant the seeds
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Slip each seed between the cup and the construction paper until it is an inch to an inch and one-half below the top edge of the cup. Pour water into the center of the paper towels until the construction paper is wet
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Watch the miracle!
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Set the seed viewer on a sunny window sill. Check at the same time each day to see what is happening. Chart the growth and development of the plant. You must keep your paper towel moist for the seeds to germinate and grow properly!
Here's another idea! Try these different experiments.
The Human Life Cycle
There are about four stages to the human life cycle (depending on how you look at it). They are Infancy, Childhood, Adolescence and Adulthood.
The four stages will be described below briefly to help you understand what the basic of the human life cycle are.
Infancy - From the age of being a newborn to the age of two years (2), you were an infant. Changes you may have experienced were more coordination (doubt you remember trying to walk and talk) and teeth growing rapidly. The body was also quite out of proportion (big head for example). These were all part of the infancy stage.
Childhood - Childhood lasts from the age of two years to adolescence (puberty). Your bones and teeth were growing rapidly and soon changes such as teeth being replaced with permanents happen. You also develop your intellectual skills (ABC's, reading/writing) and pretty much you have quite changed from being an infant.
Adolescence - Adolescence is the age where the body becomes sexually mature. Changes you may be going through are acne, increased growth and deeper voice (for boys). Girls also gain extra weight during this time. It is sometimes an emotionally distressing time for teenagers (as that's the now called term for adolescence).
Adulthood - Adulthood is the age where the body slowly slows down. Certain changes such as hair falling out and physical activity decreasing are normal as you age (thirties and above). If you are over forty, you are considered an older adult. This however doesn't stop someone from doing the things they enjoy.
What Happens If Animals Don't Reproduce?
If animals don’t reproduce they will die out. Have you heard of the word extinct?
In biology and ecology, extinction is the cessation of existence of a species or group of taxa, reducing biodiversity. The moment of extinction is generally considered to be the death of the last individual of that species (although the capacity to breed and recover may have been lost before this point). Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "re-appears" (typically in the fossil record) after a period of apparent absence.
Through evolution, new species arise through the process of speciation — where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche — and species become extinct when they are no longer able to survive in changing conditions or against superior competition. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils, survive virtually unchanged for hundreds of millions of years. Only one in a thousand species that have existed remain today.
Prior to the dispersion of humans across the earth, extinction generally occurred at a continuous low rate, mass extinctions being relatively rare events. Starting approximately 100,000 years ago, and coinciding with an increase in the numbers and range of humans, species extinctions have increased to a rate unprecedented since the Cretaceous–Tertiary extinction event. This is known as the Holocene extinction event and is at least the sixth such extinction event. Some experts have estimated that up to half of presently existing species may become extinct by 2100.
Some Cool Links
Click on any of the link buttons below to find out lots of more cool stuff about life cycles.
Have fun!!!
Pictures of Flowers In Bloom
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
