Life Cycles and the Reproduction

Life Cycle• Life Cycle – the development of an organism

from fertilization to birth, growth, reproduction, and death.– The life cycle of every organism has these 4 main

stages1. Birth – the act of bringing forth offspring.2. Growth – development; the process of growing.3. Reproduction – the process by which living things produce offspring.4. Death – the end of life.

Reproduction – the process by which living things produce offspring.

• Asexual Reproduction – a method of reproduction in which an individual of a species produces a copy of itself by dividing its cells.– Types of asexual reproduction:• Fission(cell splitting)• Spore production• Budding • Regeneration

Reproduction• Fission – reproduction by a cell dividing into 2 or

more equal parts, each of which develops into a new individual cell or organism.– Fission is common in bacteria and protozoa (animal like single

celled organisms).

Reproduction

• Spore – a single reproductive cell that when released can grow into a new plant.– Spores are released into the wind and sprout if

moisture and temperature conditions are favorable.

– Most fungi (mushrooms, mildew, and most molds) and some plants (mosses and ferns) produce spores.

Reproduction• Budding – a small growth (called a “bud”) forms

a cell or organism that develops into a new individual.– Yeasts reproduce by budding.

Reproduction

• Regeneration – a form of asexual reproduction where missing parts of an organism are regrown; in some species, entire new individuals can develop by regeneration.– If certain worms are cut in half, each half will develop

into a new worm.– Lobsters can regrow claws, and lizards can regrow

tails.• The more complex the organism, generally the

less ability it has to regenerate.

Regeneration

• Sea Star Regeneration

• Regenerative Medicine

Agar Experiment

• Which dish had the most bacteria?• Which dish had the least bacteria?• Why do you think that happened?• What does this experiment show us about

how bacteria reproduces?• How will this affect your hand washing,

cleaning, etc.?

Asexual Reproduction in plants

Cloning – a whole new plant forms from one piece of the original plant.

This can happen naturally when a plant has a bulb or runners. This can also happen when a leaf or stem cutting is taken from the plant and purposefully put in moist material to grow into a new plant that is just like the parent.

Bulb

Plant Reproduction

• Vegetative Reproduction – asexual reproduction in which some plants grow stems that branch out along the ground; nodes on these stems are where new roots can grow, starting a whole new plant.

• Examples: bulbs, runners, cutting up plants.

Vegetative Reproduction

–Bulbs – buds with short stems, modified compacted leaves for food storage, and epithelial tissue between each leaf.–Runners – stems that grow above ground in

vegetative reproduction.– Farmers cut up plants and use eyes, buds,

leaves, roots, and stems to grow new identical plants.

Most large plants must have a male and female part to reproduce. During reproduction a male gamete and a female gamete combine to create a baby plant.

When the male and female cell combine they form a fertilized egg (zygote). This egg will grow into an embryo (baby plant). This embryo is protected inside a seed.

Gamete – a cell used for reproducing. The male cell is called a sperm, the female cell is called an egg.

Zygote – a fertilized egg.

Embryo – a mature zygote in the female plant that will eventually become a seed.

Germination –the growth of an embryo in a plant.

Conifer Tree Reproduction• An example of a plant that reproduces

using male and female gametes is a conifer tree. A pine tree is a conifer tree.

Conifer – a tree or bush that has cones; usually an evergreen.

When you look at a pine tree, you may be able to see that there are both big and small cones on it. These two kinds of cones are usually found on the same tree. The small cone carries the male cells (gametes), it does not take a lot of space to carry the male cell which is pollen. Pollen from the male pine cone is carried by the wind and sticks to the larger female pine cone. The tow gametes combine to form a zygote. The fertilized egg will divide and grow to become an embryo. The embryo which is protected inside the seed will use nutrients found on the inside of the seed. When the pinecone opens, the seed drops to the ground where it can grow.

Flowering plant – uses a flower as the reproductive organ of the plant.

Pollination – transferring pollen from anther to stigma.

Reproduction of Flowering Plants

Carpel – the female reproductive structure also knows as the pistil.

Anther – the tip of the stamen, the male structure in flowering plants responsible for producing pollen needed for reproduction.

Endosperm – tissue surrounding an embryo of seeds in a flowering plant that supply nutrients to the embryo.

Fertilization – the result of a sperm and egg uniting.

Flowering plant -

Spawning – a large number of eggs are laid so that some are likely to survive egg-eating predators. Most fish and amphibians spawn.