Multicellular Organisms

National 4Unit 2Multicellular OrganismsGermination For seeds to germinate (i.e. grow), they need particular conditions:

WaterOxygenWarmthPropagation Propagation is the process by which a grower increases the yield of a particular plant.

There are two methods of propagation:VegetativeArtificialVegetativePropagation Vegetative propagation is a form of asexual reproduction in plants.

This means that the offspring formed through this type of propagation will be identical to the parent plant (a clone).Why is this important?Vegetative PropagationExamples:

Bulbs are an example ofvegetative propagation. An example of a bulb is an onion. They act as a food storefor the plant to grow from the bud.Bud(Will growInto a new plant)

Vegetative PropagationExamples:

Tubers are another example ofvegetative propagation which actas a food store. An example of a tuber is a potato.

Vegetative Propagation Some plants, like the strawberry plant, produce miniature plants called plantlets attached to the parent.

The plantlets obtain food from the parent plant until theyhave produced roots and can absorb water and minerals from the soil.

Growing PlantsSome plants can be sheltered to allow us to control the conditions they are grown in and protect them.

Polythene tunnelGreenhouseGenetics We all receive one allele for each characteristic from our mother and one from our father

The allele that is expressed in the phenotype (the physical appearance) is known as the dominant allele and the other as the recessive allele

The dominant allele is represented by a capital letter and the recessive by a lower case.

Genetics If the alleles that an individual receive from their parent are the same, they are said to be homozygous.

If the alleles from each parent are different then they are said to be heterozygous. GeneticsFor example: Purple petals (P) is dominant to yellow petals (p).

If a true-breeding (homozygous) purple plant is crossed with a yellow plant, the offspring will all be yellow. Insulin Insulin is a hormone that allows our body cells to absorb glucose from our blood.

Special cells (called beta cells) in the pancreas produce insulin and release it into the bloodstream.

When we eat a meal, the level of glucose in our blood increases. This leads to a rise in insulin. Insulin On occasion, the pancreas may not produce enough insulin or our body cells may stop responding to it.

This leads to diabetes and means we cannot control the amount of glucose in our blood.