Biology Test-12

The AB blood grouping occur due to

Whereas in the rest three cases,

(A)

(B)

(D)

The gymnosperms are the plants in which seeds are not enclosed within a fruit wall, that is they bear naked seeds.

In Gymnosperms, the male and female gametophyte does not have an independent free-living existence.

The Sequoia is one of the tallest gymnosperms while Zamia is the smallest gymnosperm known.

The plant represents the diploid saprophytic phase in the life cycles.

Gymnosperms are heterosporous, produces smaller microspore and larger megaspores. These spores are produced within the sporangia that are borne on sporophyll, arranged on the spirally along an axis to form compact or cones.

Seymouria is the connecting link between amphibia and reptiles.

They lived about 280-270 million years ago – during the early Permian period.

It is believed that it could secrete salt like reptiles from its snout and could live without water for a longer duration.

That’s why Seymouria skin was more like a reptile and less like a true amphibian.

The correct order is1(ii), 2(iv), 3(i), 4(iii).

Diffusion is a phenomenon in which molecules move from an area of high concentration to an area of low concentration. An example of this process is a gaseous exchange of oxygen and carbon dioxide between alveolar air and capillaries. The blood in the capillaries surrounding the alveoli has a lower concentration of oxygen than the oxygen in the inhaled air. Therefore, O_2​ diffused from the alveoli to the capillaries. The blood in the surrounding capillaries has a higher concentration of carbon dioxide than the inspired air. So, CO₂​ diffuses from the capillaries into the alveoli where it is then exhaled.

Syphilis is a sexually transmitted disease caused by the bacterium Treponema pallidum, transmitted through sexual contact or exchange of blood or through the placenta to a fetus.

It includes several stages- 1st stage includes infectious painless ulcers on the genitals.

The 2nd stage includes skin lesions, hair loss, swollen joints.

The 3rd stage includes blindness, heart trouble, aortic impairment.

Bee wax is formed from palmitic acid and myricyl alcohol. Waxes are esters of fatty acids with alcohol of high molecular weight instead of glycerol.

They form water-insoluble coatings on hair and skin in animals and stems, leaves and fruits of plants. Bee wax is also called as Hexacosyl palmitate by worker bees.

Vaccination is based on the property of memory of the immune system. Second-generation vaccines - These are subunit vaccines, contain defined protein antigens (such as tetanus or diphtheria toxoid) or recombinant protein components (such as hepatitis B surface antigen produced from yeast, herpes vaccine).

Phloem always flows from a sugar source to a sugar sink.

• The accepted mechanism used for the translocation of sugars from source to sink is called the pressure flow hypothesis.
• As glucose is prepared at the source (by photosynthesis) it is converted to sucrose (a disaccharide).
• The sugar is then moved in the form of sucrose into the companion cells and then into the living phloem sieve tube cells by active transport.
• This process of loading at the source produces a hypertonic condition in the phloem.

Formation of ribosomesis a function of the ''Nucleolus''.

• The Nucleolus is a spherical and membrane-less structure so that the content of the nucleolus is continuous with the rest of the nucleoplasm.
• It is the site for active ribosomal RNA (rRNA) synthesis.
• Because of the production of ribosomes nucleolus is also called the ''ribosomal factory''
• Nucleolus usually attached to chromatin (or chromosomes) at a specific site called the Nucleolar organizer region/NOR.
• The number of nucleolus in a nucleus is one. Onion cell has 4, and in oocytes of amphibians has 2000 nucleoli.
• The human cell has 5 nucleoli.

Amensalism is an association between two species where one species is harmed and other is unaffected.

Amensalism - It is a relationship between two different species of organisms, one of which is interrupted or destroyed and the other remains unaffected.

Penicillin killing bacteria is an example of amensalism.

Abducent cranial nerves is not considered as the purely afferent nerve otherwise abducent is the 6th cranial nerve which is considered as purely efferent nerve.

The afferent nerves receive signal from a sensory organ and sent it to CNS for processing.

The efferent nerves carry signals from the CNS to the effector organ. The nervous system has two main parts:

• The central nervous system(CNS)
• The peripheral nervous system(PNS)

The main feature of heterosis is:

The F1 hybrid obtained will exhibits superiority over both parents in yield, adaptation, quality and maturity because when two plants having different characters are crossed the F1 hybrid can acquire the superior desired characters of both the parents. For example, one parent has a higher yield while the other parent has greater disease resistance now the F1 progeny obtained may acquire both the characters and become superior.

Heterosis results in phenotypic superiority like increased height, yield and fertility but it is totally under genetic control because all these characters are expressed by the concerned genes only. The possible genetic causes of heterosis are: Partial to complete dominance, overdominance & epistasis. The superiority is reproducible in a specific environment only

Therefore, the correct answer is ''all of these''