While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment. - Biology

Advertisements
Advertisements
Short Note

While creation and presence of variation is directionless, natural selection is directional as it is in the context of adaptation. Comment.

Advertisements

Solution

Creation and variation occur in a sexually reproducing population as a result of crossing over during meiosis and random fusion of gametes. It is however the organisms that are selected over a period of time which are determined by the environmental conditions. In other words, the environment provides the direction with respect to adaptations so that the organisms are more and more fit in terms of survival.

  Is there an error in this question or solution?
Chapter 7: Evolution - SHORT ANSWER [Page 49]

APPEARS IN

NCERT Exemplar Biology Class 12
Chapter 7 Evolution
SHORT ANSWER | Q 4. | Page 49

Video TutorialsVIEW ALL [1]

RELATED QUESTIONS

Mammals : _________ : : Amphibia : Fishes


State the connecting links between Peripatus with Annelida and Arthopoda.


What are vestigial organs?


(a) Select the analogous structures from the combination given below:

(i) Forelimbs of whales and bats

(ii) Eyes of octopus and mammals

(iii) Tuber of sweet potato and potato

(iv) Tuber of Bougainvillea and tendrils of Cucurbita

(b) State the kind of evolution they represent


Given below is the list of vegetables available in the market. Select from these the two vegetables having homologous structures:

Potato, sweet potato, ginger, radish, tomato, carrot, okra (Lady’s finger)

(A) Potato and sweet potato

(B) Radish and carrot

(C) Okra and sweet potato

(D) Potato and tomato


Study the following statements:-

I. Wings of birds and wings of bats are homologous organs.

II. Wings of birds and wings of insects are modified forelimbs.

III. Wings of birds and wings of insects are analogous organs.

IV. Wings of birds and forelimbs of horse are homologous organs.

The correct statements are

(A) I and II

(B) II and III

(C) III and IV

(D) I and IV


Write the similarity between the wing of a butterfly and the wing of a bat. What do you infer from the above with reference to evolution? 


How analogy and homology considered as an evidence in support of evolution ?


State a reason for the increased population of dark coloured moths coinciding with the loss of lichens (on tree barks) during industrialization period in England.


Four students P, Q, R and S differently reported the following set of organs to be analogous :

P. Forelimb of a frog and forelimb of a lizard

Q. Forelimb of a bird and forelimb of a human

R. Wings of a parrot and wings of a butterfly

S. Wings of a bird and wings of a bat

The two students who have reported correctly are :

(A) P and Q

(B) Q and R

(C) R and S

(D) P and S


 An example of homologous organs is


Give the importance of fossil in support of organic evolution


Name the scientists who Discovered the fossil of Australopithecus


Explain the evolution of giraffe's neck according to Lamarck's theory of evolution.


Name any two temporary embryonic structures in vertebrates which provide evidence for evolution.


What are homologous organs?


How do homologous organs help in providing evidence for organic evolution?


Human tailbone is a vestigial organ. Explain.


Wing of an insect and forelimb of a bird are :
(a) analogous organs
(b) analeptic organs
(c) homologous
(d) homophobic organs


The organs P and Q of two animals have different structures but similar functions. On the other hand, the two organs R and S of two other animals have the same basic structure but different functions.
(a) What are the organs like P and Q known as?
(b) Name the organs like P and Q. Also name the animals which have such organs.
(c) What are the organs like R and S called?
(d) Name the organs like R and S. Also name the animals which have such organs.


Identify the following pairs as homologous and analogous organs:
(i) Sweet potato and potato
(ii) Eye of octopus and eye of mammals
(iii) Thorns of Bougainvillaea and tendrils of Cucurbits
(iv) Fore limbs of bat and whale


In a class, students were asked to observe the models/slides/pictures of the skeletons of forelimbs and wings of different organisms. After the observations the students made the following groups of homologous structures. Select the correct group :
(A) Wings of a bird and a butterfly
(B) Wings of a pigeon and a bat
(C) Wings of a butterfly and a bat
(D) Forelimbs of a cow, a duck and a lizard


Write short notes based upon the information known to you.

Connecting link


Write the names of those animals in whom the human body organs are functioning.


Observe the picture and answer the following questions.
A) Which evidence of evolution is shown in the picture?
B) What can be proven with this proof?
C) Give one more example of evidence of evolution


_______ is a connecting link between Annelida and Arthropoda.


Complete the following chart:


With the help of diagrams, describe emasculation and bagging. 


The most common types of fossils are ------------------------. 


Draw a labelled diagram of T.S. of a leaf showing Kranz anatomy. 


What do you mean by vestigial structures? Name four vestigial organs found in man.


Choose the correct option of the following question:

Wings of Insect and Birds are examples of :


Explain any three molecular (genetic) evidences in favour of organic evolution.


Define fossils. 


Differentiate between connecting links and the missing links.


Define phylogeny.


Short answer question.

Give the significance of fossils.


Explain the importance of Anatomical evidences with examples.


_____________ is a vestigial organ in human beings.


Find an odd one out.


Find an odd one out.


Find an odd one out.


I am a connecting link between reptiles and mammals. Who am I?


Name the parts shown in the diagram.
Human jaw


The decaying process of C-14 occurs continuously in dead organisms only.


Match the following.

Column A Column B
1) Morphological evidences a) Tail-bone or wisdom teeth
2) Paleontological evidences b) Leaf venation
  c) Fossils

Give scientific reason.

Peripatus is said to be the connecting link between Annelida and Arthropoda.


Enlist the evidences of evolution.


Observe the given images and answer the following questions.

  1. Which evolutionary evidence does it indicate?
  2. What does it prove?
  3. State another example of evolutionary evidence.

Which evidence of evolution is shown in the given picture? Explain the importance of this evidence.


Observe the following images and answer the questions.

  1. Which evolutionary evidences are indicated in the given picture?
  2. How are they formed?
  3. Which method is used to measure their age or their time?

Explain any five types of evidence that support the theory of evolution.


Write the answers to the questions by observing the figure below.

(a) (b) (c)
  1. Write the name of the animal ‘(a)’ in the figure.
  2. Write the name of the animal ‘(b)’ in the figure.
  3. Write the name of the animal ‘(c)’ in the figure.
  4. Which evolutionary evidence is illustrated by this figure?
  5. Write the definition of that evidence for evolution.

Biogenetic law states that ______.


The degenerated and non-functional organs found in an organism are called ______.


A human hand, a front leg of a cat, a front flipper of a whale and a bat’s wing look dissimilar and adapted for different functions. What is the name given to these organs?


How do you differentiate homologous organs from analogous organs?


Select vestigial organs from the following.


Homologous organs and vestigial organs are examples of ______ type of evidence in evolution.


Select the correct statement.


Select the CORRECT match.


Select the CORRECT set of homologous organs.


Which of these is not a vestigial organ in human beings?


The fossil remains of Archaeopteryx is a connecting link between ______ 


Where is carbon dating used?


Evolution has exhibited a greater stability of molecular structure when compared with morphological structures. Comment on the statement and justify your opinion.


Homologous organs are:


Cucurbits do not develop thick and woody stem as they are:


Tendons and ligaments are examples of ______.


Palaeontological evidence for evolution refers to the ______.


Basic principles of embryonic development were pronounced by:


Study of fossils is ______.


Evolutionary convergence is the development of:


The process of mating of individuals, which are more closing related than the average of the population to which they belong is called ______.


The presence of gill slits, in the embryos of all vertebrates, supports the theory of ______.


Which is not a vestigial organ in a man?


Flippers of Penguins and Dolphins are examples of: 


The study of fossil evidence of evolution is called ______


Organs having similar functions but different origin and development are known as:


Appearance of antibiotic-resistant bacteria is an example of ______.


What were the characteristics of life forms that had been fossilised?


Did aquatic life forms get fossilised? If, yes where do we come across such fossils?


How do we compute the age of a rock?


I am the connecting link of annelida and arthropoda. What is my name?


Write down the difference between homologous and analogous organs.


Explain natural selection with the example of industrial melanism.


Evolutionary convergence is the development of a ______.


Write avian characters of Archaeopteryx.


Write a note on the significance of Palaeontology.


Industrial melanism was highlighted by ______.


Industrial melanism in England after 1850 is an excellent example of Natural selection. Explain how?


Complete the following conceptual picture:


Give examples of homologous organs and analogous organs in plants.


Pick the odd man out:


Share
Notifications



      Forgot password?
Use app×