LAMARCK's THEORY
Jean Baptiste Lamarck (1744-1829) proposed a theory which was published in "<em>Philosophie Zoologique"</em> (1809). This theory is simply known as Lamarckism. It has two main postulates:
1. Use and disuse of organs
2. Inheritance of acquired characters.
Example
He explained his theory by giving the examples:
1. Neck length of Girrafes
2. Webbed toes of water birds, and
3. Wings of penguins
Explanation
Lamarck explained that water birds use toe for swimming, with the passage of time webbed were developed in their toes. these features were then transferred to their offspring.
Drawback
Lamarck theory was based on natural observation. It did not explain the genetic basis of such characteristics.
Answer: The correct answer is-
an agent that causes a mutation in DNA.
Mutagen is an agent or a substance that causes permanent change in the genetic material of living organisms ( DNA, deoxyribonucleic acid). This process is called mutation.
A mutagen can be a chemical, physical or biological agent that causes mutation in the DNA.
Example- Physical agents such as -
- Ionizing radiations like alpha particles, gamma rays, X-rays that brings break in the DNA and cause other damages.
- Ultraviolet radiations that creates pyrimidine dimers ( T=T) and causes replication errors if damage is not repaired.
Answer: A community is all of the populations of different species that live in the same area and interact with one another. A community is composed of all of the biotic factors of an area. An ecosystem includes the living organisms (all the populations) in an area and the non-living aspects of the environment.
X ( inherited ) chromosomes!!!!!!!!!!!!!!!!!!!!!
The right answer is: <span>D. the formation of clouds
</span>Condensation is the second stage of the water cycle. The water vapor circulating in the atmosphere will encounter a colder air and it will turn into droplets, this phenomenon is called condensation.<span>
Water droplets accumulate in the form of clouds of different shapes, density, and altitude. This phenomenon is called condensation. Water vapor travels on the surface of the earth in the form of clouds.</span>
