Asexual reproduction in animals.

Asexual reproduction occurs when a single organism reproduces without the genetic input of another. Because of this, a single individual organism is able to produce a nearly exact copy of itself. Asexual reproduction is common among living things and takes a variety of forms.

Bacteria and Binary Fission

Many single-celled organisms rely on binary fission to reproduce themselves. All bacteria reproduce by binary fission. They simply go through mitosis and split in half.

Fragmentation and Black worms

Many species of annelids (worms) reproduce via an asexual process called fragmentation. Included in this category of worms are California blackworms, or mudworms. These worms are hermaphroditic -- they have both male and female reproductive parts -- and can reproduce sexually. However, many times these worms will reproduce using fragmentation. In this case, blackworms can break apart and each consequential fragment can become a new worm.

Regeneration

Regeneration is similar to fragmentation. A star fish for example is able to grow from a piece of the parent.

Budding and Hydras

Hydras are a type of freshwater cnidarian related to jellyfish, sea anemones and corals. Hydras reproduce asexually by developing small, genetically identical polyps that protrude from the parent. These polyps break off from the parent to form a new organism in a process called "budding."

Asexual reproduction in plants

It is possible for plants to reproduce asexually (i.e. without flowers or fertilization). Two of the most important methods of asexual reproduction are:

• runners - e.g. strawberry, spider plant

• tubers, bulbs- e.g. potatoes, dahlias

Humans are able to propagate plants by artificial propagation. Taking cuttings and grafting are the methods of artificial propagation which you need to know. They are a quick way of propagating large numbers of identical plants.

Plants which are produced in these ways are genetically identical to each other and to the parent; a group like this is called a clone.

A clone is a group of cells or organisms which are genetically identical to each other.

Advantages for the plant of asexual reproduction:

• only one parent plant is required

• young plants are identical to the parent, so that good features will always be passed on

it is faster

Disadvantages: The entire species can be wiped out due to a disease.

Vocab words: budding, regeneration, runners, grafting, rhizomes and tubers.

Activity 1: open Asexual Gateways reading Copy the chart on paper and complete the activity.

asexual gateways reading_wksht.pdf (124k)

Activity 2 Brain pop: Asexual Reproduction> Take the quiz first on a scrap piece of paper. DO NOT LOOK AT YOUR RESULTS. Then watch the movie and retake the quiz. See if your score improves.

Add files