Topic 2The World of Plants Standard Grade Biology
World of Plants is divided into: A- Introducing plants B- Growing plants (Pollination, Fertilisation, Asexual reproduction) C- Making food
The life cycle of a plant • There are 7 stages in the life cycle of a plant. seed / fruit Formation seed dispersal fertilisation pollination germination flower formation development
Seed Structure • Parts are: Seed coat Forms a tough protective layer Embryo shoot Embryo – grows into plant Food store Provides the embryo plant with food. Embryo root
Seed Dissection • Using a scalpel, carefully dissect your seed in half lengthways. • Draw a diagram of what you can see. • Identify the parts, and label your drawing (workbook p13).
Investigation: Germination • This is an Exam Board Investigation that makes up part of your Practical Abilities grade (20% of finals) • Planning may be done in small groups but after this you must work on your own • Write in your Investigation booklet.
What affects germination? • 3Bio2 Brainstorm 16/03/07 • Spacing / number of seeds • Humidity / water volume • Type of seeds • Size of seeds • Type of soil / mass • Temperature • Depth of planting • Gases / oxygen levels • Measure by % germination after set time
Germination and Temperature • Example of results table. Also draw a graph. • What conclusions can you draw from your experiment? • How could you have improved it?
Germination conditions • Germination is the development of a new plant from the embryo in a seed. • Seeds need certain conditions to germinate: • Water • to activate enzymes which digest stored food • Oxygen • Needed for the production of energy for germination • Warmth • Needed for the enzymes to work effectively.
Germination and Temperature • The best temperature for germination of a species of plant is known as the optimum temperature. • The optimum temperature is normally between 15oC and 30oC.
Petal Anther Stigma
Carpelfemale parts Stigma Petals Stamen male parts Style Anther Ovary Filament Ovules Nectaries Sepals Collect a cut-out flower, colour it in and put it together.
What do the parts do? Sepals- protect the flower when it is a bud Stamen- anther produces male sex cells (pollen) Carpel- stigma traps pollen Style is where pollen tube grows down to female sex cells. Petals- colourful to attract the insects Nectaries- give out sugary liquid to attract insects Carpel- ovary produces female sex cells (ovules)
Quick Test • Why is the seed coat important? • Name the parts of the embryo plant. • Why is the food store in a seed important? • Name the three factors required for germination. • Where are a plant’s sex organs found? • Name two parts of a flower that attract insects. • Name the male part of a flower. • Which part of the flower contains ovules? • Which part of the flower produces pollen? • Which part of a flower catches pollen grains?
Pollination • Pollination involves the transfer of pollen (male gamete) from the anther to the stigma (outermost female part) • If it is in the same flower it is called self-pollination. • If between different flowers it is called cross-pollination • Plants are pollinated by insects or the wind.
Pollination Activity • Look at the Botanics Posters • Which features are from wind pollinated or insect pollinated plants? • Workbook p28 • Construct a table to show the differences between insect and wind pollinated plants.
Pollination Summary dull bright colour light sticky dangling inside flower feathery sticky none makes sugar
Hayfever World of plants workbook G – pages 34 &35 C- pages 36 & 37 • Answer Q 1 – 5 on hayfever and • Answer Q 1 – 5 on pollen in the air from Feb - Sept
Fertilisation • Fertilisation involves the fusion of the nucleus of the male gamete (in the pollen) with the nucleus of the female gamete (in the ovules).
Pollen tubes • The pollen grain grows a tube. • The tube reaches an ovule. • The gamete nuclei fuse (fertilisation) and a zygote (seed) forms.
Fertilisation Once fertilisation has taken place the zygote (fertilised ovule)becomes a seed, and the ovary becomes a fruit. The petals die and fall off. The plant seeds are in the fruit.
What are fruits like? • The fruits can be: • - soft & fleshy • - hard & dry • What fruits can you think of? • What are their seeds like? • Draw a table with headings for each type and write some examples for them.
Seed Dispersal- why? • Seeds must be carried away (dispersed / scattered) from the parent plant to: • Reduce overcrowding • Reduce competition for: • - Water • - Light • - Nutrients
Activity • Cut out the seeds, match and stick them into appropriate columns in a table, for: Wind Animal (external) Animal (internal) • [There is also mechanical (eg broom, sea cucumber) and water (eg coconut) but you don’t need to know them for Standard grade]
Activity • Listening exercise on seed dispersal • Listen to the tape, • Use the commentary to help you answer questions on your handout. World of Plants Workbook p41 Comparing Lime and Sycamore seeds. Go through the problem solving activity
Quick Test-A • What term is used to describe male and female gametes? • What is pollination? • Name the two types of pollination. • Describe the differences in the pollen between insect and wind pollinated plants. • Explain why the stigmas of wind pollinated flowers hang outside the flowers.
Quick test-B • Why do wind pollinated flowers not produce nectar? • How does the male gamete reach the female gamete? • What is a fruit? • Name three ways in which fruits and seeds are dispersed. • Why is it important that fruits and seeds are carried away from the parent plant?
Types of reproduction Sexual reproduction Involves 2 parents and sex cells ie. pollen and ovule join to make a new individual. • Asexual reproduction • Involves 1 parent and no sex cells. • Ways they naturally reproduce include: • - Tubers • - ( Bulbs ) • - Runners
Taro- Japanese potato Tubers Tubers are underground food stores which stores food over the winter and provides a new plant with food until it can make its own. Examples: potato, artichoke, yam, cassava, water chestnut, arrowroot Food made by the new plant is sent to make new tubers. Thereby reproducing itself.
Arrowroot arrowroot = arrow root = Chinese potato (this name also is used for jicama) = goo = seegoo = arrowhead = Chinese arrowhead = tse goo = ci gu = tsu goo Notes: The name arrowroot is more commonly associated with a thickener that's made from the plant. A fresh arrowroot tuber looks like a small onion, only without the layers. It should be peeled, and then it can be boiled or stir-fried. Look for it in Chinese markets during the winter.
Cassava cassava = casava = manioc = mandioca = tapioca root = yucca = yucca root = yuca root = Brazilian arrowroot Pronunciation: kuh-SAH-vuh Notes: People in Hispanic countries use cassavas much like Americans use potatoes. There's both a sweet and a bitter variety of cassava. The sweet one can be eaten raw, but the bitter one requires cooking to destroy the harmful prussic acid it contains.
tapioca root Topinambour Topinambour Water chestnut Chinese water chestnut Notes: Water chestnuts are delightfully sweet and crisp- if you buy them fresh. You need to peel off their brown jackets and simmer them for five minutes before stir-frying. Tinned Water chestnuts are easily available but not nearly as good. If you use them, blanch them first in boiling water for thirty seconds.
Keukenhof gardens near Amsterdam Holland. Bulbs Bulbs are also underground food stores which work in the same way as tubers. The difference is that bulbs have thick fleshy ‘leaves’.
Stargazer lily Examples: snowdrop, crocus, daffodil, iris, lily, hyacinths, amaryllis, onion, garlic.
1. Sept.- Oct. Planting TimeThe tulip bulbs are going to be planted twice as deep as the bulb is high. They have no roots at this stage. 4. Feb. – March Growing PeriodThe bulbs begin to change as the starch, or carbohydrates in them turns to sugar. As this occurs, the leaves and flower gradually push up-wards out of the bulb. 2. November Making RootsThe roots start growing out of the base, establish themselves taking nutrients from the soil. Mother bulbs get ready for winter. 5. April – May Blooming TimeThe tulips are in bloom-they receive their nourishment from the roots-only the brown skin of the bulb remains as all of the energy has gone to the bloom. 6. May – JuneRegenerationAfter flowering the blooms are cut and the leaves are left on the plant. The new daughter-bulbs use the food in the leaves to grow. 7. July - Sept.MultiplyingUp to five small bulbs can be expected to grow out of the mother bulb. They form their roots slowly, and develop their blooms and leaves within the bulb, for next year's plant. 3. Dec. - Jan.Cooling PeriodRest period. In order for bulbs to bloom in the spring they need weeks of at least 5oC. Frost at this time doesn’t harm them.
Runners Runners are side shoots which grow out from the parent plant. Buds form at points along the runner and eventually these buds form roots and grow into new plants. Examples: spider plant (Anthericum), strawberry (Fragaria x ananassa)
Flame violet (Episcia reptans) Collect Information Card “Asexual Reproduction” Take short notes from it.
Activity World of plants workbook Read p20 “Advantages of asexual reproduction” Read p32 & 33. • Copy and complete the table. Summarising advantages & disadvantages of sexual versus asexual reproduction