Name 2 plants that produce pollen in early Spring in UK?
Crocus and Snowdrop
Name the secretion from the bodies of Aphids?
Honeydew
Define Pollination and Fertilisation in flowering plants.
Pollination - Is the transfer of pollen by an agent, e.g. a honey bee, from the ANTHER to the receptive STIGMA usually of another plant of the same species.
- Fertilisation is the fusion of the male gamete (from the pollen) with the female gamete (in the ovule) to produce a single cell called a zygote.
- Pollen has to be accepted by the stigma. It must be the correct species and from a different plant (for cross pollination).
- Pollen grain sticks to the stigma.
- Once accepted the inner skin (intine) of the pollen absorbs moisture from the stigma rupturing the apertures in the outer skin (extine).
- The intine now grows through the extine and forms the pollen tube. Enzymes are produced by the pollen tube which enable the pollen tube to grow and move rapidly down the style canal to the ovary.
- The tube enters the ovary through the micropyle and the two nuclei in the pollen tube are released.
- One of these fuses with the female sex cell to form the zygote. The second fuses with another nucleus in the ovule, called the primary endosperm nucleus, which produces a structure that divides and develops into a food store called the endosperm which nourishes the developing embryo plant.
What is meant by cross pollination
eg An APPLE
Pollen from different plants of the same species transferred onto a STIGMA.
Cross Pollination
Methods
Self-incompatability - eg an APPLE
Stigma will not accept pollen from same flower. The apple requires another tree of different variety but
flowering at same time. Types A-B-C-D, Early-mid season-mid/latelate
Protandry -Stamens ripen before stigma. This is more
common as in Rosebay Willow Herb (Chamerion
augustifolium)
Protogyny - Stigma develops before the stamens.
Outline methods used by plants to favour cross pollination - 6 marks
Name 6 from list below:
Self incompatibility
PROTANDRY - STEMENS ripen before STIGMA matures
PROTOGYNY - STIGMA matures before STAMENS
HETEROSTYLY - Stigma and Stemens situated at different levels in flower to prevent self pollination.
MONOECIOUS Plants have ing single sex flowers, but both sexes on the same plant.
DIOECIOUS plants is a single sex found on a plant.
STAMINATE are flowers having only male parts
PISTILLATE are flowers having only female parts.
Which part of a flower protects it prior to opening
SEPAL
Name a plant that produces honey that granulates rapidly
Oil Seed Rape (OSR), Ivy
How does the WHITE CLOVER flower show the bees that it has been pollinated.
flowers awaiting pollination point upwards whilst those that have been pollinated recurve and droop downwards.
Name 1 plant with extra floral nectaries and where on the plant they are located
Plum - extra floral nectaries are located along the edge of the plant leaf.
Broad Bean - highly variable in the number of large, dark purple spots on the light green stipules, at
the base of the leaf petioles (leaf stalk)
Cherry Laural - Two pairs of extra floral nectaries are found on the underside of the leaf, on either side of the
central leaf vein close to the leaf stem. If attacked by a fungus they appear as four black spot.
Cherry Prunus - extra nectaries are located on the upper side of the leaf and are red looking like cherries.
Name a flower that changes colour when it has been pollinated
Horse Chestnut has White flowers which turn to Yellow when they open up. But once pollinated the flower turns to pink. Stemens wither once pollinated.
Forget-me-not blue flower with yellow ring, yellow ring fades to white when pollinated.
(15) List the factors affecting nectar secretion, using an example to illustrate each of your points.
- Position of the flower on the plant. Nectars at the bottom secrete more than those at the top e.g. Rosebay willow herb (Chamaenerion angustifolium).
- Age of the flower. Bramble flowers opening first on an inflorescence produce more nectar than those further up. The new young shoots of Ling heather that has been burnt produces more nectar than flowers on old wood plants.
- Temperature. Blackberry (Rubus fruticosus) is not fussy. Lime (Tilia spp) likes warm nights and humid, humid days for best secretion.
- Time of day. Poor secretion early in the morning then peaks as wind and sun evaporate some of the water. Nectar quality and quantity may peak at different times. Apple (Malus spp) most visited later in the day.
- Wind and humidity. Light wind and low humidity can concentrate nectar. Strong drying wind and very low humidity can cause nectar to dry up.
- Soil moisture. If this drops to the level where plants wilt, nectar production will cease. Deep rooted plants fare best. Long term issue with weather in previous months being key.
- Nature of soil and subsoil. Acidity and alkalinity can influence nectar production. Heather (Calluna vulgaris) needs acid soil. Blackberry does well on either. Lack of potassium in the soil will reduce nectar supply, so the best nectar producers are those grown on soil that is well balanced with potassium, phosphorous, calcium and nitrogen.
- Topography. Heather and clover both yield better on slopes.
- Shading. Some plants really need sunshine (Sedum spp).
Monoecious
Male & female flowers on same plant e.g. Hazel
Flowers separated
Flowers may ripen at different times sp
Less likely to self-pollinate
Definition of Extra-floral nectaries.
Extra-floral nectaries (areolar glands) are glands, located in places other than the flowers. Extra floral nectaries consist of patches of glandular tissue found on the cotyledons, on the trunk,leaves, stipules, bracts, petioles etc. of certain species of plant. Sometimes they are barely distinguishable from the surrounding plant tissue.
