Answer: Option B. -> artificial selection
:
B
Broccoli has been cultivated from wild cabbage by the method of artificial selection by the farmers. Green coloured flowering heads of broccoli are edible. The wild cabbage was bred and selected for this character to get broccoli.

Answer: Option A. -> True
:
A

Genetic variation is a measure of the genetic differences that exist within a population. It is the basic phenomenon on which environmental forces act to create evolution among populations.

Answer: Option B. -> Species C existed before species B
:
B

Following conclusions can be drawn by observing the figure.
  1. Species A is the most recent species because it is located on top.
  2. Species B is more abundant than species C as its fossils are found in two layers of the sedimentary rock.
  3. Deeper the layers, older are the fossils. So, fossils of species C are older than the fossils of species B. Thus, species C existed before species B.
Different layers of earth provide information about geological time scale. Scientists link the fossils and the geological time scale information to know the time of existence of those species.

Answer: Option B. -> XY
:
B
Humans contain 22 pairs of autosomes and 1 pair of sex chromosomes. The female gamete or the egg consists of an “X” chromosome. If this is fertilised by a sperm containing “X” chromosome, the baby will have “XX” chromosome and will be a female. But if the egg is fertilised by a sperm containing “Y” chromosome, the baby will have “XY” chromosome and will be a male.

Answer: Option C. -> DNA similarity
:
C

Common origin of man and chimpanzee is best shown by DNA similarity.  According to DNA studies, DNA of humans and chimpanzees is 98% similar. Humans and chimpanzees share a common ancestry.

Answer: Option A. -> Forelimbs of a dog and flipper of a whale
:
A and B
Homologous organs are those which have similar structure and origin but different function. Forelimbs of a dog and flippers of whale have similar structure and origin but they serve a different funtion, thus, homologous. Similarly, arms of a rabbit and a human are homologous organs.
Wings of a moth and a bird, although serve a common function, do not share a similar structure and hence analogous. Same is the case with limbs of a lizard and a crab. 

Answer: Option B. -> Natural selection
:
B
When a population of a particular variant organism increases due to a survival advantage, it is the natural selection. In this case, green beetles cannot be seen by the crow and therefore, their population has grown compared to the red coloured beetles. Thus, natural selection pressure is exerted by crows. 

Answer: Option B. -> variation
:
B
Variation is the degree of differences in the progeny and between the progeny and the parent. Variations can be seen either in the morphological appearance (phenotype) or the genetic makeup (genotype) of an organism.

Answer: Option B. -> Modern forms of life may have evolved from earlier forms of life
:
B

Speciation is the formation of new species from the pre-existing ones. Since the fossils are found in different layers of sedimentary rock, It is evident that older layer contains older species and the newer layers contain newer species. The newer species are formed by changes or modifications in the older species. Thus, the similarities of fossils suggests the evolution of new species from the pre-existing ones.

Answer: Option A. -> True
:
A
$\bullet$ Set of observable characteristics in an organism is known as phenotype.
$\bullet$ An organism's phenotype is the morphological representation of its genotype. 
$\bullet$ Few examples of phenotype are: Eye colour in humans, height in humans, flower colours in plants, height of plants, etc.