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It is explained by Mendel in the form of Law of Independent Assortment. This law states that when two pairs of traits are combined in a hybrid, segregation of one pair of characters is independent of the other pair of characters. It was based upon the observation in the dihybrid cross.

Miller & Urey has performed an experiment to proof chemical origin of life. They postulated that first organic cell would have been produced from inorganic (chemicals) substances. 

They took a glass jar and tried to create an internal environment same as that of earth's environment billions of trillions year ago. 

In a sterile jar they insert methane (CH₄), hydrogen (H₂), water (H₂O) & ammonia (NH₃). They heat the jar to increase its temperature to match up the earth's temperature million years back & also increases the pressure. They even provided some electric current to that jar. After some days, the solution starts turning pink because of the formation of some organic compounds. 

This experiment gave some evidences of formation of life from some inroganic/chemical sources.

Homologous organs are the organs present in different organisms which have the same origin but perform different functions. Examples of Homologous organs include wings of bat, wings of birds, dolphin, flipper and human arm. By observing them we can conclude that they all have the same origin and during the course of evolution they started performing different functions as per their needs and requirements. They all are derived from the same set of bones which are humerus, radius, ulna, carpals, metacarpals and phalanges but now all of them function differently.

The variation are produced when the new generation reproduces, The second generation produced will have variations that they inherit from the first generation. The organism can reproduce through two mode of reproduction

(i) Asexual reproduction. 

(ii) Sexual reproduction. 

In Asexual reproduction is found by the division of parent organism into daughter nuclei. In case of bacteria, bacteria get divided into two individuals, each of them will divide again and give rise to two other organism. The four individual bacteria generated would be very similar with minor difference that occurred due to small inaccuracies in copying of DNA. 

In Sexual reproduction involves the fusion of gametes. The offsprings show variations from their parents due to crossing over and exchange of gene segments. They are not exact copies of their parents, due to environmental factors certain favourable variations are also produced. Due to production of variations, sexually reproducing animals show very quick evolution.

(i) A. Organs or features can be adopted to new functions during evolution Example-Feathers were developed from providing insulation in cold Weather (in Dinosaurs) but in birds they were adopted for flight.

B. “Older body design are not efficient”. Example-simplest form like Bacteria, which inhibits most inhospitable habitat like, hot springs, deep sea, thermal vents and ice in antarctica. 

(ii) The study of classification of various organisms gives us an idea about the evolutionary history of the organisms, which have certain similar characteristics are placed in one group. It can be thus concluded that the organisms placed in one group may have evolved from common ancestors and may have a common evolutionary history.

The accumulation is the variations of gradual changes which takes places in primitive organisms over millions of years and new organisms are formed. 

There are four ways in which this can do. These are:- 

(i) Natural selection: Natural selection may work differently in different location. Due to this, variations may occur which lead to the formation of a new species. 

(ii) Geographical isolation: is the isolation of population by physical barriers such as stretches of water, mountain, etc. 

(iii) Dna changes: variations during DNA copying often leads to the formation of a new species 

(iv) Genetic drift: Over generations, genetic drift may lead to the accumulation of different changes which leads to the formation of a new species.

(i) There is a resemblance in most of the photos of her relatives because they had inherited the same genes with slight variations from their parents. 

(ii) Gregor Mendel has given laws of inheritance which explains the passing of characters from parents to their progenies. There are 3 laws of inheritance.

These are:-

a) The law of dominance 

b) The law of segregation 

c) The law of independent assortment 

(iii) Katy is a practical girl. She believes more on practical approaches that is why, after studying evolution & inheritance, she tried to find out its reality by observing it in her own family.

(i) INHERITED TRAITS:- characters which an organism get through its parents in his genome. They are lifetime traits & cannot be altered.

ACQUIRED TRAITS:- traits which we acquire or generates in our whole life time. They are inheritable because they are not related to our genome. 

(ii) the tattoo is an acquired trait which Amit's mother has done in during her lifetime. This trait hasn't affected her genome & thus is inheritable. Due to this reason, Amit doesn't have that tattoo which her mother had. 

(iii) Amit is a curious child, who doesn't hesitate in asking his doubts. It is a very good quality of Amit which will help him in taking decisions without any doubt or unclarity. 

Moreover, he used to be a keen observer who has noticed the presence to tattoo on his mother's arm and absence of that tattoo on his arm.

Formation of new species because of barriers, genetic drift and natural, selection takes place which leads to complex structure with a better survival advantage. This is known as evolution. The traits, which are acquired including the life time of an organism affect the structure and functioning of cells, tissues, and organs without affecting genetic material and thus are not inherited.

Tracing evolutionary relationships between organisms is called as phylogeny while studying structures of various DNAs to establish evolutionary relationships between them is called as, while studying structures of various DNAs to establish evolutionary relationships between them is called as molecular phylogeny. 

The sequence of base pairs in a DNA molecule decides the characteristics of an organism. A slight change in this sequence can bring very large changes in certain organisms. 

For e.g. - DNA of Homo sapiens (i.e. humans) are 99.9% same. That is, only a 0.1 % difference in humans' DNA can create so many variations. Similarly, population of different unrelated species is very different in their molecular organization too. 

DNA of humans has some similarity with DNA of apes, and due to this reason, it is assumed that they might have some common ancestors.

 The correct answer is Gametes.

Variation is not hereditary from generation to generation. In case of Asexual reproduction DNA will not transfer to germ cells. So experiences of an individual during its lifetime cannot be passed on to its progeny and cannot direct evolution.

(a) The character which gets expressed in the presence of its contrasting form is termed as a dominant trait.

(b) The trait which remains unexpressed in the presence of its contrasting form is called a recessive trait.

(i) Green colour.

(ii) 25%

(iii) 3: 1.

The characteristics or traits in animals and plants are controlled by genes. For example the transmission of color of hair from the parents to the child. If a mother has black hair and the father has blonde hair and the child has black hair then the transmission of genes for hair colour from the mother and father to the child is as follows: Mother’s cell contains two genes HH for black hair. Both the genes HH are dominant genes, so the mother has black hair. Father’s cell contains two genes (hh) for blonde hair. The two genes hh are recessive genes, so the father has blonde hair. Now, during the process of reproduction, the mother transmits one of the dominant genes H for black hair to the child and the father transmits one of his recessive genes h for blonde hair to the child. Due to this, the child has the genes Hh for her hair. Now the gene H for black hair is the dominant gene but the gene h for blonde hair is the recessive gene. The dominant gene H for black hair shows its effect due to which the child has black hair.

Comparing the DNA of different species gives a direct estimate of how much the DNA has changed during the formation of these species. Thus, it helps us to a great extent in tracing the evolutionary pathways.

23 pairs of chromosomes are present in human beings. 

• There are similarities in the structure and anatomy of different animal groups. E.g. human hand, forelimb of bull, patagium of bat and flipper of whale are all similar in their internal anatomy. There is similarity in the bones and joints of all these specimens.
• External morphology does not show any similarity. Use of each of the organ is also different in different animals. Structurally, they may not be related.
• However, the similarities in the anatomy is an evidence that they may have a common ancestor.
• In this way, the anatomical evidence throws light on the process of evolution.

These evidences are as follows:

• Morphological evidences
• Anatomical evidences 
• Vestigial organs 
• Palaentological evidences 
• Connecting links 
• Embryological evidences.

DNA molecule is made up of two helical strands consisting of deoxyribose sugar, phosphoric acid and pairs of nitrogenous bases. These three together is called a nucleotide.

1. Theory of evolution:

• According to the theory of evolution, first living material was in the form of protoplasm which was formed in ocean.
• Gradually, it gave rise to unicellular organisms. Changes took place in these unicellular organisms which made them evolve into larger and more complex organisms.
• All evolutionary changes were very slow and gradual taking about 300 crore years to happen.
• Different types of organisms were developed as the changes and development that occurred in living organisms wefts all round and multi-dimensional.
• Hence, this overall process of evolution is called organizational and progressive.
• Variety of plants and animals developed from the ancestors having different structural and functional organization during the process of evolution.

False. (Changes acquired during life time are not heritable. They are not transferred to next generation. Only the genes are transferred to the next generation.)

False. (The theory of natural selection which mentions ‘Survival of fittest’ is given by Darwin.)

False. (Humans walking upright existed in Africa and China, Indonesia of Asian continent too.)

True. (Each species has specifically evolved characters due to evolution and speciation.)

Consider tallness as a characteristic. Plant height depends upon particular plant hormone which in turn will depend on the efficiency of the process for making it. If the enzyme responsible for the production of this hormone is efficient, the plant will be tall. If the gene for that enzyme has an alteration that makes the enzyme less efficient, the amount of hormone will be less and plant will be short.

The mRNA formed in nucleus comes in cytoplasm. It brings in the coded message from DNA. The message contains the codes for amino acids. The code for each amino acid consists of three nucleotides. It is called as ‘triplet codon’. Each mRNA is made up of thousands of triplet codons. As per the message on mRNA, amino acids are supplied by the tRNA. For this purpose, tRNA has ‘anticodon’ having complementary sequence to the codon on mRNA. This is called ‘translation’.

Evolution of upright man continued in the direction of developing its brain for the period of about 1 lakh years and meanwhile he discovered the fire. Brain of man 50 thousand years ago had been sufficiently evolved to the extent that it could be considered as member of the species Homo sapiens. Neanderthal man can be considered as the first example of wise man. The Cro-Magnon man eyolved about 50 thousand years ago and afterwards, this evolution had been faster than the earlier. About 10 thousand years ago, wise-man started-to practise the agriculture. It started to rear the cattle-herds and established the cities. Cultural development took place later

Genes present in the form of DNA along with RNA control the structure and functioning of the body.

In the figure, the process of mutation is shown. The original nucleotide sequence of TGC is replaced by new mutated sequence GAT. The change in the nucleotide sequence will change the DNA.

This will result in the change in genes and then changing the hereditary characters. Due to such

change in genes, the evolution proceeds. The mutation so formed can be minor or major. The greater the impact of the change, the evolution takes place rapidly. The mutation thereby produce recombinations leading to diversity.

i. AUG is the initiation codon, which is present on the mRNA.

ii. There are two molecules of tRNA present inside the ribosome. The triplet codons present on them are UAC and AAG respectively.

iii. The mRNA that leaves the nucleus has genetic code: A U G U U C A A A 

The genetic code on DNA therefore should be as follows: T A C A A G T T T

• The picture is based on the Lamarck’s principle of ‘use and disuse of organs’.
• The morphological characters of organism develop because of specific activities that the organisms perform.
• If some organ is not used it gets degenerated. If excessively used, it develops further.
• Thus, the morphological changes take place due to activities or non-working of a particular body parts in an organism. Due to constant extension of neck to eat foliage from the top of the trees, giraffe’s neck became long.

i. Embryological evidences of evolution are shown in this picture.

ii. The similarities in the initial embryonic stages of different vertebrates shows that there was a common origin of all of them. Thus embryological evidences prove that there was common vertebrate ancestor.

iii. Palaeontological evidences such as vestigial organs and connecting links are another examples of evolutionary evidences.

Some living organisms possess some characters in them which are the distinctive features of different groups or phyla. Such individuals connect these two groups by sharing the characters of both and hence they are known as connective links.

Examples: 

(1) Peripatus: Peripatus is the connecting link between Annelida and Arthropoda. It shows characters of both animal phyla. Like annelid worm, it shows segmented body, thin cuticle and parapodia. Like an arthropod, it shows open circulatory system and tracheal system for respiration.

(2) Duck Billed platypus: This is a connecting link between reptiles and mammals. Like reptiles it lays eggs but like mammals it has mammary glands and hairy skin.

(3) Lung fish: Lung fish is a connecting link between fishes and amphibians. Though a fish, it shows lungs for respiration as in amphibian animals.

(4) Connecting links indicate the direction and hierarchy of evolution.

The answer is (c) TtWW.

चक्रासन से निम्नलिखित लाभ होते हैं-

1. यह रीढ़ की हड्डी को लचीला बनाकर वृद्धावस्था नहीं आने देता तथा दाँतों को सक्रिय बनाता है।

2. शरीर में स्फूर्ति एवं शक्ति बढ़ाता है।

3. यह श्वास रोग, सिरदर्द, नेत्र विकार, सर्वाइकल तथा स्पोंडोलाइसिस में विशेष हितकारी है।

4. यह हाथों तथा पैरों की मांसपेशियों को मजबूत बनाता है।

योग शब्द ‘युज’ से बना है। युज का अर्थ होता है जोड़ना या मिलाना। योग के द्वारा, कार्य करते समय शरीर व मन में ताल-मेल बैठता है। योग एक प्रकार का आसन करने का अभ्यास है। योगाभ्यास करने से शरीर और मस्तिक दोनों स्वस्थ रहते हैं।

सर्वाग आसन करने का तरीका-

1. पीठ के बल सीधा लेट जाएँ। पैर मिले हुए हों, हाथों को दोनों ओर बगल में सटाकर हथेलियाँ जमीन की ओर करके रखें।

2. श्वास अन्दर भरकर पैरों को धीरे-धीरे 30 अंश फिर 60 अंश और अन्त में 90 अंश तक उठाएँ। इसके बाद लगभग 120 अंश पर पैर ले जाएँ। हाथों को कमर के पीछे लगाएँ, कोहनियाँ भूमि पर टिकी हुई हों और पैरों को मिलाकर सीखा रखें।

3. पुन: पैरों को सीधा रखते हुए पीछे की ओर थोड़ा झुकाएँ। दोनों हाथों को कमर से हटाकर भूमि पर सीधा कर दें। अब हथेलियों से भूमि को दबाते हुए जिस क्रम में उठे थे उसी क्रम में धीरे-धीरे पहले पीठ और फिर पैरों को भूमि पर सीधा करें।

कोणासन करने का निम्नलिखित तरीका है-

1. सर्व प्रथम अपने दोनों पैरों को अगल-बगल फैलाकर खड़े हो जायें। तत्पश्चात् दायें हाथ को सिर के ऊपर ले जाते हैं।

2. कमर का हिस्सा आगे-पीछे नहीं होना चाहिए।

3. इस आसन को 10 सेकेण्ड तक 4-5 बार कर सकते हैं।

सिंहासन या व्याघ्रासन करते समय यदि सम्भव हो तो सूर्य की ओर मुख करके वज्रासन में बैठकर घुटनों को थोड़ा खोलकर रखें। हाथों की अंगुलियाँ पीछे की ओर करके पैरों के बीच सीधी रखें। श्वास अन्दर भरकर जिह्वा को बाहर निकालें। सामने देखते हुए श्वास को बाहर निकालते हुए सिंहवत् गर्जना कीजिए। यह क्रिया 3-4 बार करनी चाहिए।

हलासन करने से निम्नलिखित लाभ होते हैं-

1. यह मेरूदण्ड को लचीला बना देता है तथा कब्ज को दूर कर पाचन शक्ति को बढ़ा देता है।

2. इसके अभ्यास से अकड़े हुए कन्धे, कोहनी, गठिया एवं पीठ दर्द ठीक हो जाता है।

1. During ETS, NADH₂ and FADH₂ undergoes oxidation where they are converted to NAD⁺ and FAD⁺ respectively. 

2. During this conversion, hydrogen is removed, which latter forms proton and electron. This electron so formed is passed on to different electron carriers. During this transfer of electron, energy is released which is used in ATP synthesis. 

3. In case of NADH_2, energy is released at three places hence results into formation of 3 ATPs whereas, in case of FADH₂ energy is released at only two places, hence results into formation of only 2 ATPs. 

4. Here, the ATP formation occurs by Chemiosmotic hypothesis.

The correct answer is (D) Succinyl Co-A → Succinic acid

The correct answer is (C) 3 ATPs

The correct answer is (B) 1

The correct answer (A) Oxaloacetic acidis 

1. Pyruvate dehydrogenase 

2. Thiamin (vitamin Bi)

Respiratory substrates are the molecules that are oxidized during respiration to release energy which can be used for ATP synthesis. Carbohydrates, fats and proteins are the common respiratory substrate. Glucose is the most common respiratory substrate.

The correct answer is (D) Inner mitochondrial membrane