BIOLOGY 1.5 Marks Questions

Homologus organs are those organs which have the same basic structural design and origin but have different functions. For example, The forelimbs of humans and the wings of birds look different externally but their skeletal structure is similar. Analogus organs are those organs which have the different basic structural design and origin but have similar functions.
For Example, the wings of birds and insects.

(a) Pyramid B is for stable population and pyramid C is for declining population.
(b) The age pyramids are plotted on the basis of individuals in a population under the categories. Prereproductive age, Reproductive age and Postreproductive age.

A method known as multiple fission is adopted by the unicellular organism Amoeba to survive and reproduce under unfavourable conditions. When the conditions are unfavourable, Amoeba withdraws its pseudopodia and becomes almost round. It secretes a hard covering called cyst.

Wings of butterfly and wings of birds are analogous as they share common function but won't have the same structure.
As the convergent evolution creates analogous structures that have similar function.

The thorns of Bougainuillea are similar in their basic structure, origin and development to the tendrils of cucurbita. But their function, their texture are different. Thorns of Bougainvillea are for protection, the tendrils of cacurbita help the plant to groul by supporting it.

Differences between divergent and convergent evolution :

Divergent Evolution	Convergent Evolution
1. Development of different functional structures from a common ancestral form is called divergent evolution.	Development of similar adaptive functional structures in unrelated groups of organism is called con - vergent evolution.
2. Homologous organs show divergent evolution.	Analogous organs show convergent evolution.

Difference between Lamark and Darwin's theories

Lamarckism	Darwinism
1. This theory was anticipated by Jean Baptiste de Lamarck.	This theory was anticipated by Charles Darwin.
2. Individual population has identical characteristics. Individuals can make a difference.	The interbreeding population of individuals always has similar characteristics with certain variablility. Individuals are eternal. The population will turn itself. Variation does exist regardless of the condition of the organism.
3. Internal drive towards greater complexity, influenced by the inheritance of properties acquired. Variations are tailored to the needs of the orgaism. Eg: The long neck of a giraffe.	Eg: Keen eyesight of the hawak.

Difference between Ramapithecus and Dryopithecus.

Ramapithecus	Dryopithecus
1. The Ramapithecus were more man like.	The Dryopithecus were ape like individuals.
2. They evolved in 15 mya.	The evolved in 25 mya.
3. They were found in 'Miocene epoch'.	They were found in the 'Siwalik Hills'.
4. They have competitively smaller brain but larger brain development.	They have larger brain but the development of brain is lesser when compared to the Ramapithecus.

Adaptation is the evolutionary process where an organism becomes better suited to its habitat. This process takes place over many generations. An example is the adaptation of horses' teeth to grinding grass. Grass is their usual food; it wears the teeth down, but horses' teeth continue to grow during life.

(a) Both were similar to chimpanzee.
(b) Both bowed down and walked.

Adaptive radiation is the relatively fast evolution of many species from a single common ancestor. Adaptive radiation generally occurs when an organism enters a new area and different traits affect is survival. An example of adaptive radiation is the development of mammals after the extinction of dinosaurs.

The theory of spontaneous generation states that life arose from non-living matter. Louis Pasteur is credited with conclusively disproving the theory of spontaneous generation with his famous swan-neck flask experiment. He subsequently proposed that "life only comes from life."

Missing link, hypothetical extinct creature halfway in the evolutionary line between modern human beings and their anthropoid progenitors.

In allopatric speciation, groups from an ancestral population evolve into separate species due to a period of geographical separation. In sympatric speciation, groups from the same ancestral population evolve into separate species without any geographical separation.

The organs of the body of the organisms which are non-functional but were functional in their early ancestors are called as the vestigial organs. Coccyx, third eyelid, vermiform appendix in man. Atavistic organs are those vestigial organs which have become functional e.g. Birth of human baby with a small tail, development of power of moving pinna in same persons and presence of additional mammae in some human beings.

Hardy-Weinberg principle states that allele and gene frequencies in a population will remain constant from one generation to the next if certain conditions are kept constant. These conditions are :
(i) Population is large
(ii) Random mating
(iii) Absence of mutation
(iv) All members in a population are living and reproduction rate is constant.
Two factors that affect Hardy-Weinberg equilibrium are : 
(i) Mutations, (ii) Gene Migration.

Geological time scale (GTS) : GTS is chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists and other earth scientists to describe the timing and relationship between events that have occurred throughout earth's history.
The name of eras are following : (i) Cenozoic,(ii) Mesozoic, (iii) Paleozoic, (iv) Neo-proterozoic, (v) Meso-proterozoic, (vi) Paleo-proterozoic