Biology Test - 48

Larva of jellyfish (Aurelia) is called Planula.

Jellyfish is a transparent, soft-bodied marine animal, umbrella-shaped, and of gelatinous appearance.Larva of jellyfish (Aurelia) is known as Planula. It is the free-swimming, flattened, ciliated, bilaterally symmetric larval form.It is cylindrical or egg-shaped, and cilia present on its body helps in locomotion.However, planula is the least developed stage in the jellyfish life-cycle.

Lichens are the symbiotic association between algae and fungi. The algal cells, through the process of photosynthesis, provide the fungus with some of the organic nutrients which it needs. The fungus also plays a vital role in providing a physical structure to shelter the algae from excess sunlight and in particular, water loss.

Cyclosporin A is used forImmunosuppression.

Cyclosporin A is a powerful immunosuppressive agent whose lack of myelotoxicity makes it unique among nonsteroidal drugs currently given for immunosuppression.Cyclosporine are used with other medications to prevent transplant rejection attack of the transplanted organ by the immune system of the person who received the organ in people who have received kidney, liver, and heart transplants.

Estradiol is secreted by graafian follicle and theca externa.

The graafian follicle is a fluid filled cavity which is present adjacent to the oocyte. It contains Granulosa and theca cells which continuously divide. It produces estrogen. The production of estrogen requires both the cells of the theca interna and granulosa cells.

The theca externa is a connective tissue layer derived from fibroblast-like cells that produce extracellular matrix factors, such as collagen. The theca interna and externa also contain a rich supply of blood vessels called the vascular tissue that brings nutrients, oxygen, and immune cells to the growing follicles.

(A) Monohybrid Cross : Monohybrid crosses are those that involve one pair of contrasting traits. In monohybrid crosses, the phenotypic ratio of the F2 generation is typically 3:1 (III).
(B) Dihybrid Cross : Dihybrid crosses are those that involve two pairs of contrasting traits. In dihybrid crosses, the phenotypic ratio of the F2 generation is typically 9:3:3:1 (IV).
(C) Incomplete Dominance : Incomplete dominance is when neither allele for a specific trait is dominant over the other. As a result, the phenotype of the heterozygote is somewhere in between the two homozygotes. The phenotypic ratio in such a case is typically 1:2:1 (II).
(D) Test Cross : A test cross involves crossing an individual exhibiting the dominant phenotype (but unknown genotype) with a homozygous recessive individual. The phenotypic ratio can be 1:1 (I) if the dominant individual was a heterozygote. If the dominant individual was a homozygote, all offspring will exhibit the dominant phenotype.

The number of chromatids in a chromosome at anaphase is1 in mitosis and 2 in meiosis.

Anaphase:

• At the start of the Anaphase, the replicated chromosomes, called sister chromatids, are adjusted along the equator of the cell on the central plane. The sister chromatids are sets of indistinguishable duplicates of DNA joined at a point called the centromere.
• During anaphase, each pair of chromosomes is isolated into two indistinguishable, autonomous chromosomes. The chromosomes are isolated by a structure called the mitotic axle. The sister chromatids are isolated all the while at their centromeres. The isolated chromosomes are then pulled by the axle to inverse posts of the cell.
• Meiosis happens in two phases meiosis I and meiosis II. During meiosis I, homologous chromosomes independent and the quantity of chromosomes in daughter cells get reduced to half. This division is known as reductional division.
• Equational division is the main cell division in meiosis, the cycle by which germ cells are framed. In decreasing division, the chromosome number is diminished from diploid (46 chromosomes) to haploid (23 chromosomes), called first meiotic division and first meiosis.
• During meiosis II, centromere parts and the chromosome number continues as before in the daughter cells. Thus, meiosis II is known as equational division. It doesn't lessen chromosome numbers. An atomic division that keeps up a similar ploidy level of the cell.

The correct answer is To ensure fertilization.

The first step in the process of reproduction is the fusion of a sperm and an ovum.

When sperms come in contact with an egg, one of the sperms may fuse with the egg. Such fusion of the egg and the sperm is called fertilization.

During fertilization, the nuclei of the sperm and the egg fuse to form a single nucleus. This results in the formation of a fertilized egg or zygote.

Gestation (pregnancy) can be defined as the time duration between conception and birth (delivery) of the fetus. It includes the development of the embryo in the uterus.

Implantation - It is the process of attachment of the zygote to the uterus lining.

Klinefelter's syndrome is caused due to the presence of an additional copy of X-chromosome resulting into a karyotype of 47,XXY. Such an individual has overall masculine development, however, the feminine development is also expressed. Such individuals are sterile. Thus, statement B and E are correct regarding Klinefelter's syndrome.
Statement A, C and D are incorrect w.r.t. Klinefelter's syndrome as they are associated with Down's syndrome.

Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants.

Stephen Hales is considered the 'father of plant physiology' for the many experiments he conducted in 1727; though Julius von Sachs unified the pieces of plant physiology and put them together as a discipline.

Pteridophyta is the only division of sub-kingdom cryptogamae that can reproduce both, sexually by the formation of spores as well as sexually by the formation of gametes.‘Cryptogams’ is the term used for plants that do not form flowers and seeds. So, it is assumed that their reproduction is hidden as they produce spores.