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Genes are specific sequences of bases on a DNA molecule, located on a particular chromosome, and code for proteins. A chromosome has more than one genes.

Farmers were able to grow present day cabbage, cauliflower, and broccoli from wild cabbage by selective breeding. Broccoli was selected by breeding larger flower stalks and cabbage was bred by selecting shorter petioles. Cauliflower is also a descendant of wild cabbage. It was bred by selecting sterile flowers.

Flower: Bracteate, bracteolate, bracteoles usually large, pedicellate, heterochlamydeous, complete, bisexual, pentamerous, zygomorphic and hypogynous.

 (d) Artificial selection

Wild Cabbage.

Molecular Taxonomy is the branch of phylogeny that analyses hereditary molecular differences, mainly in DNA sequences, to gain information and to establish genetic relationship between the members of different taxonomic categories.

Allozymes, mitochondrial DNA, micro satellites, RFLP (Restriction Fragment Length Polymorphism), RAPD (Random amplified polymorphic DNA), AFLPs (Amplified Fragment Length Polymorphism), Single nucleotide Polymorphism – SNP, microchips or arrays.

The uses of molecular taxonomy: 

1. Molecular taxonomy helps in establishing the relationship of different plant groups at DNA level. 

2. It unlocks the treasure chest of information on evolutionary history of organisms.

The answer is (a) one

23^rd pair of chromosome determines the sex of the offspring hence it is called as sex chromosome

(a) Girls only

It is the genetic variation in small populations caused by a specific environmental factor.

The answer is (c) both similarities and variations with parents

(a) Fossils represent modes of preservation of ancient species.
(b) Fossils help in establishing evolutionary traits among organisms and their ancestors.
(c) Fossils help in establishing the time period in which organisms lived.

(1) Fossils offer palaeontological evidence for the evolutionary process.

(2) Due to some natural calamities the organisms get buried during ancient times.

(3) The impressions and remnants of such organisms remain preserved underground. The hot lava also traps some organisms or their impressions. All such formations form fossils.

(4) Study of fossils help the researcher to understand the characteristics of the organisms that existed in the past.

(5) Carbon dating method also helps in finding out exact age of the fossil. According to the structure of earth’s crust the fossils are obtained at specific depths.

(6) The oldest ones are obtained at the depth while the relatively recent ones occupy the upper surface. Thus fossils of invertebrates were seen in very old Palaeozoic era. Later were seen fossils of Pisces, Amphibia and Reptilia. The Mesozoic era was dominated by reptiles while Coenozoic era showed presence of mammals.

(7) In this way, study of fossils unfold the evolutionary secrets.

Botanical gardens play the following important roles.

1. Gardens with aesthetic value which attract a large number of visitors. 

For example, the Great Banyan Tree (Ficus benghalensis) in the Indian Botanical Garden at Kolkata. 

2. Gardens have a wide range of species and supply taxonomic material for botanical research. 

3. Garden is used for self-instruction or demonstration purposes. 

4. It can integrate information of diverse fields like Anatomy, Embryology, Phytochemistry, Cytology, Physiology and Ecology. 

5. Act as a conservation centre for diversity, rare and endangered species. 

6. It offers annual list of available species and a free exchange of seeds. 

7. Botanical garden gives information about method of propagation, sale of plant material to the general public.

The uses of Herbarium:

1. Herbarium provides resource material for systematic research and studies. 

2. It is a place for orderly arrangement of voucher specimens. 

3. Voucher specimen serves as a reference for comparing doubtful newly collected fresh specimens.

4. Voucher specimens play a role in studies like floristic diversity, environmental assessment, ecological mechanisms and survey of unexplored areas. 

5. Herbarium provides opportunity for documenting biodiversity and studies related to the field of ecology and conservation biology.

International Code of Nomenclature is based on the following six principles.

1. Botanical nomenclature is independent of zoological and bacteriological nomenclature. 

2. Application of names of taxonomic group is determined by means of nomenclatural types. 

3. Nomenclature of a taxonomic group is based on priority of publication. 

4. Each taxonomic group with a particular circumscription, position and rank can bear only one correct name, the earliest that is in accordance with the rules except in specified cases. 

5. Scientific names of taxonomic groups are treated as Latin regardless of their derivation. 

6. The rules of nomenclature are retroactive unless expressly limited.

The significance of Molecular Taxonomy:

1. It helps to identify a very large number of species of plants and animals by the use of conserved molecular sequences. 

2. Using DNA data evolutionary patterns of biodiversity are now investigated. 

3. DNA taxonomy plays a vital role in phytogeography, which ultimately helps in genome mapping and biodiversity conservation. 

4. DNA – based molecular markers used for designing DNA based molecular probes, have also been developed under the branch of molecular systematics.

Wild cabbage is the odd term of the given four terms.

Wild cabbage is the ancestral plant from which after artificial selection gives broccoli, cauliflower, and kale.

Almost all the human traits show variation. Variations occur in the generations of sexually reproducing organisms. 

The two human traits that show variation are as follows: 

i) Ear lobes: free and attached earlobes, is closely attached to the side of the head in some of us and not in others. Free and attached are two variants found in human being. 

ii) Eye color: from black to brown to blue to hazel brown, there are so many shades of eye colours found in the human population.

Evolution is the scientific term used for 'Science of heredity and variation.'

Genetically acquired traits are the ones which we inherit from our previous generation. They depend upon the genetic material. Of the given traits in the question eye color and height are the genetically inherited traits whereas physical strength is the acquired trait, the one acquired over a course of time.

Variation refers to the difference in the characterstic or traits among the individuals of a species. 

Variation is beneficial to the species because: 

1. It enables the organism to adapt themselves in changing environment. 

2. It forms the basis of heredity. 

3. It forms the raw materials for evolution and development of new species. 

Thus accumulation of variations in a population led to population to adapt to the changes and the new needs. This provide survival advantage to the species

When different animals which have organs originated from the same part of the body but function differently then they are known as homologous organs. 

Example: wings of a bat, wings of birds, dolphin, flipper and human arm are the homologous organs. They all are derived from the same set of bones which are humerus, radius, ulna, carpals, metacarpals, and phalanges. But all of them function differently.

Natural selection is a nature’s phenomenon in which the species which inherits variations and has better chances of survival are allowed to reproduce and produce a large number of offsprings. The term was given by Charles Darwin.

XX: female 

XY: male 

Human females have two X chromosomes whereas the human male has one X and one Y chromosome. 

Thus females are homogametic

The plant used by Gregor Mendel for his experiments on genetic was a sweet pea. The scientific name of the plant is Pisum sativum.

Genetic drift is a phenomenon more common in the small population which may lead to the accumulation of different changes which lead to the formation of different species. 

The accidental survival of the beetles of one colour that changed the common characteristics of the resultant population So accidental change in the small population can change the frequency of some gene in the population example accidental red beetles get crushed by elephant while green survived led to genetic drift which change the colour of the population to green.

The human being with XY pair of chromosomes is called a male. The sex of the human offspring is determined by the set of chromosomes inherited from father.

Sclereids are dead cells, usually these are isodiametric but some are elongated too. The cell wall is very thick due to lignification. Lumen is very much reduced. The pits may simple or branched. Sclereids are mechanical in function. They give hard texture to the seed coats, endosperms etc.

Correct Answer is: (d) Hartig

Correct Answer is: (b) Nageli

Correct Answer is: (a) Nageli

Correct Answer is: (c) glandular

• Fossils are the preserved ancient species 
• Fossils help determine evolutionary differences between organisms and their ancestors.
• Fossils determine the living period of specific species.

(i) Both Mendelian factors, which are now known as genes and chromosomes are found in pairs.

(ii) Both segregate at the time of gamete formation, during meiotic cell division. 

(iii)The paired condition is again restored after fertilization.

Male individual have 46 chromosomes but because the gametes are always haploid i.e., they have half the number of chromosomes; sperms will be haploid (23 chromosomes). Female individual also contains only 23 chromosomes in egg. It is the fusion of the sperm and egg which leads to an offspring with 46 chromosomes.

Organic evolution is the process or event of a change in an organism by which descendants differ from their ancestors.  

Evolution cannot be equated to progress. From lower forms to higher forms it gives rise to more complex body designs even while the simpler body designs continue to flourish. For example, human beings have not evolved from chimpanzees but both have a common ancestor.

Analogous organs are those organs which I have different basic structural design and developmental origin but have similar appearance and perform similar functions. 

Example: The wings of birds and bats look similar but have different design in their structure. They have a common function of flying but their origins are not common. So, birds and bats are not closely related.

Dissimilarities between members of the same species is called variations. Two offsprings of the same parents show certain variations. Variations occur due to sex chromosomes. Variations arising in germplasm (genes) of the organism are heritable. Mother and father contribute to the gene pattern of the offsprings through their chromosomes, in which recombination occurs at the time of gametogenesis. In zygote formation, gene pattern of both parents come together, that causes some variations between parents and offsprings and amongst offsprings also.

In these examples, the temperature at which the fertilized eggs are incubated determines whether the offspring will be a male or a female.

Correct option (A) A random change in gene frequencies occurring by chance fluctuations   

Explanation:

The elimination of the genes, of certain traits, from the small population when a section of the population dies of natural calamity or migrates to other region is called genetic drift. lt alters the gene frequency of the population.

Evolution cannot be equated with progress because it seems to have just given rise to more complex body designs. For example bacteria still flourish in spite of a very simple body design while dinosaurs did not survive in spite of complex design. Thus evolution is simply the generation of diversity and shaping of diversity by environmental selection.

Evolution is simply generation of diversity and the shaping of the diversity by environmental selection. It is not as if the newly generated species are in any way better than the older one. It is just natural selection and genetic drift have together led to the formation of a population that cannot reproduce with the original one, as in case of the evolution of humans and chimpanzees from a common ancestor. 

In evolution the new forms evolved are more complex than their ancestors. It is the adaptability of a species to the environment that supports its survival not the complexity of the species. Each species, whether complex or simple is subjected to natural selection. Each species has to go through the process of natural selection to survive and reproduce. In evolutionary terms, we cannot say that a particular species has a better design than another. Each species is well suited and adapted to its environment and hence is good enough to live and reproduce.

Evolution is simply the generation of diversity and the shaping of the diversity by environmental selection. Species adapt to the conditions available in their environment. Some older and simple species live on quite effectively. The only progressive trend in evolution seems to be that more and more complex body designs have emerged over time. In fact, one of the simplest life forms like bacteria - inhabit the most inhospitable habitats like hot springs, deep-sea thermal vents and the ice in Antarctica

Fibres are very much elongated sclerenchyma cells with pointed tips. Fibres are dead cells and have lignified walls with narrow lumen. They have simple pits. They provide mechanical strength and protect them from the strong wind. It is also called supporting tissues. Fibres have a great commercial value in cottage and textile industries.

One or two layers of continuous or discontinuous tissue present below the epidermis, is called hypodermis. It is protective in function. In dicot stem, hypodermis is generally collenchymatous, whereas in monocot stem, it is generally sclerenchymatous. In many plants collenchyma form the hypodermis.

Stomata are minute pores surrounded by two guard cells. The stomata occur mainly in the epidermis of leaves. In some plants addition to guard cells, specialised epidermal cells are present which are distinct from other epidermal cells. They are called Subsidiary cells. Based on the number and arrangement of subsidiary cells around the guard cells, the various types of stomata are recognised, The guard cells and subsidiary cells help in opening and closing of stomata during gaseous exchange and transpiration.

Between meristematic tissue and permanent tissue:

There are many types of epidermal outgrowths in stems. The unicellular or multicellular appendages that originate from the epidermal cells are called trichomes. Trichomes may be branched or unbranched and one or more one celled thick. They assume many shapes and sizes. They may also be glandular (eg: Rose, Ocimum) or non – glandular.