Biology Test 323

The process of formation of one or more species from an existing species is called Speciation. It is of two types, mainly: Divergent speciation and Transformation speciation. Speciation was one of the main theories of Darwin.

One of the drawbacks of mutation theory was that it couldn’t explain the development of mimicry, the relationship between the position of nectars in flower and also length of proboscis in their insect pollinators. The problem was that these cannot be imagined to have developed all of a sudden.

The chromosomal pattern in the amniotic fluid is detected using the technique called amniocentesis. This chromosomal pattern is called karyogenesis and can be used to detect the nature of chromosomes. Hence it can be exploited to determine sex of the fetus.

Cleavage involves repeated cell division without increase in size. But cell size decreases In placental mammals (including humans) where nourishment is provided by the mother’s body, the eggs have a very small amount of yolk and undergo holoblastic cleavage. Other species, such as birds, with a lot of yolk in the egg to nourish the embryo during development, undergo meroblastic cleavage.

Metamorphosis is a process of series of changes of form from larva to adult after embryonic development. Regeneration is defined as replacement, repair or restoration of the lost or damaged structures or reconstitution of the whole body from a small fragment of it during the post-embryonic life of an organism. Growth is the result of greater anabolic (synthetic) processes over the catabolic (destructive) processes in the organism. Ageing may be defined as the progressive deterioration in the structure and functions of the cells, tissues and organs of an organism with the advancing age.

In racemose type of inflorescence, the main axis continues to grow, and the flowers are borne laterally in an acropetal succession. This means that the oldest flowers are at the base and the youngest at the top, allowing continuous growth and flowering.

Fetal sex determination is based on the patterns of chromosomes in the amniotic fluid present around the embryo. Hence this test is called amniocentesis.

Reproductive and Child Health Care (RCH) programs were developed to cover a considerable range of reproduction-related issues. These did not encompass abortion. Abortion does not determine reproductive health.

The phenomenon in which female gamete develops into embryo without getting fused with male gamete (fertilisation) is called parthenogenesis.

Autogamy is a form of self-fertilisation in which fission of the cell nucleus occurs without division of the cell, the two pronuclei so formed reuniting to form the synkaryon.

Parthenocarpy is the production of fruit without fertilisation of an egg in the ovary. Synkaryon is a nucleus formed by the fusion of two pre-existing nuclei.

Syngamy refers to physical union of male and female gamete.

Oogamy is the sexual reproduction involving the formation and subsequent fusion of a large, usually stationary, female gamete and a small motile male gamete. The female gamete may contain nourishment for the development of the embryo, which is often retained and protected by the parent organism.