Science Focus Topic 3 Notes: Plant Reproduction and Breeding | Print |
Selective breeding means that people choose specific plants with particular characteristics and encourage these plants to reproduce.

Apple Varieties
Did You Know (p.116)
There are over 7500 varieties of apples grown in the world - of which 2500 are grown in North America

Plants are also bred for ...
their ability to withstand certain environmental conditions (hardiness)
how much food they produce (yield)
their resistance to disease.
their appearance (sweetheart cherries - Summerland Research Station, B.C.)

New Genes?

Canola was developed using selective breeding and originated from a plant called rapeseed. It was developed to produce seeds that created a good-tasting oil. Canola crops are now more resistant to diseases, drought and even certain chemicals.

Scientists can change plants by going inside an individual plant cell and modify some of its material, by removing parts of the cell that control particular characteristics. This genetic material ( genes of the plant ) can then be combined with genetic material from another plant to create a new plant - having characteristics from both plants. This process (biotechnology) is called genetic modification, or genetic engineering.

Types of Plant reproduction

Plants can reproduce in two very different ways. Sexual reproduction involves the production of seeds and fruits from specialized cells of two plants. Asexual, or vegetative reproduction, occurs when a 'parent' plant grows new plants from its roots, stems, or leaves.
Traditional types of vegetative reproduction include:
layering (runners)
fragmentation (buds and root systems)

Seed Plant Reproduction (p. 93)

In vegetative reproduction, plants produce new plants identical to themselves. In sexual reprocution - reproduction using seeds - the new plants are slightly different from their parents.


The cone is the part of the tree that has a series of woody scales, and come in various shapes and sizes. Both male and female cones are produced by cone-bearing trees. Female cones contain ovules (eggs) - the small bumps at the end of a scale in a cone. Pollen grains (containing sperm) develop on the smaller male cone. Wind carries the pollen grains to the female cones. Although most of the pollen grains never reach the female cones, those that do get caught in the sticky fluid near the ovule. A pollen tube grows to the ovule and sperm is able to ferilize the egg. The process of pollination is complete. Female cones of pine trees matrure, open, and release their seeds during the fall or winter months. (This whole process takes at least two years) The seeds can then be dispersed by various methods and when they get covered they can eventually sprout and become new pine trees.


Flowers use color, scent, nectar to attact animals, so that the pollination process can begin.

Flowering Plant Reproduction

Flower Structure - A Web Quest

Parts of a Flower

Identify the Flower Parts

Flower part



brightly colored parts of the flower to attact insects and birds


green, protect the flower before it opens
(underneath after it opens)

stamen (male reproductive organ)


where pollen is produced and stored

pollen grains

cases containing male reproductive cells


stalk that supports the anther

pistil (female reproductive organ)


sticky 'lip' of the pistl that captures pollen grains


stalk that supports the stigma


swollen base of the pistil containing ovules


sacs containing female reproductive cells

Pollination (good visual description at: )

Pollination can occur by self-pollination or cross-pollination.
The bee spreads pollen over more crops than any other insect. Artificial pollination can also be used to breed different varieties of plants for specific purposes (usually to produce a better yield, or one that is more resistant to environmental conditions - such as cold winters) It is not just exposure to cold temperatures that kills seeds, but prolonged exposure to cold temperatures.

From Seed to Fruit

Once a plant is pollinated, a seed is formed. Seed Parts include the living plant (embryo) and the food suppy (cotyledon). The length of time a seed is able to stay alive varies according to the conditions it experiences. The longest-lasting seed was frozen for over 10,000 years before it sprouted and even flowered (p.125).


A fruit is the growing ovary of the plant that swells and protects the developing seeds of a plant, until they are ripe. Not all fruits can be eaten though - a cotton boll is a fruit. (uses for non-edible fruits)

Seed Dispersal

Dispersal is the transportation of seeds away from the parent plant.
It can happen in various ways (see pictures on p. 127), including:

waterways (rivers, streams, etc.)
bird droppings
animal fur

Spreading and Harvesting Seeds in the Field

Farmers use machines to disperse seeds. Once they have grown into the crop, they are harvested in two steps. A swather cuts the plants and lays them in rows (the stubble - what is left of the plant after being cut - prevents the plant from touching the soil, so the seeds can ripen). A combine then separates the grain from the rest of the plant. (The grain seeds are collected and the straw is baled, or spread evenly over the field).


When the seed is able to come in contact and get covered by the soil, it remains inactive until the right conditions are present for it to germinate. Germination is the development of a seed into a new plant. (Figure 2.39 p. 128 - Germination of a bean seed) .
Topic 1 Review p. 130

Wrap-Up (Topics 1-3) p. 131