Tag: zoology

Earthworms are hermaphrodite animals, meaning that both testes and ovary are present in a single body but cross-fertilisation is the rule. At the time of reproduction two worms come to lie close to each other and exchange sperms. The sperms are stored in pouches called spermatheca. So, the correct answer is option C.

Metamorphosis is the process of development of organisms after hatching or birth. Insects that go through three stages of change in their life cycle have an incomplete metamorphosis. The first stage is the egg. During this time, the insect will hatch into a form, called a nymph. The nymph is basically a small version of the adult insect. Once a nymph outgrows its exoskeleton it will go through a process called moulting which is to leave the old skin or exoskeleton behind. The new skin will harden and become the new exoskeleton. This will happen many times until the insect finally becomes an adult. So, the correct answer is option B.

Binary fission is the asexual form of reproduction in which single-celled organism divides itself into two cells, in favourable condition.
Multiple fission is the asexual form of reproduction where the parent amoeba cell divides to give many daughter cells in unfavourable condition.
Thus, the correct answer is option B.

Sponges and Cnidarians are among the animals, that can reproduce by budding. A small part of the parent's body separates from the rest and develops into a new individual. Sometimes the buds remain attached and become more or less independent members of a colony. In some tunicate colonies, different individuals are connected by root-like structures called stolons. In others, they share body parts, such as their atrial (exhaling) siphon. These tunicates reproduce asexually through budding example Botryllus schlosseri. The scyphistoma reproduces asexually, producing similar polyps by budding, and then either transforming into a medusa or budding several medusae off from its upper surface. The medusae are initially microscopic and may take years to reach sexual maturity. So, the correct answer is option D.

Parthenogenesis (virgin development) is a form of asexual reproduction in which an unfertilized egg develops into an adult animal. The adult is typically haploid. Parthenogenesis is common among insects (especially honeybees and wasps, aphids etc.) and crustaceans; it also occurs among some other invertebrate and vertebrate groups, including some species of nematodes, gastropods, fishes, amphibians, and reptiles. Although a few species appear to reproduce solely by parthenogenesis, in most species episodes of parthenogenesis alternate with periods of sexual reproduction. Parthenogenesis may occur for several generations, followed at some point by sexual reproduction in which males develop, produce sperm and mate with the females to fertilize their eggs. In some species, parthenogenesis is a means of rapidly producing individuals when conditions are favorable.

Parthenogenesis refers to the development of an individual from unfertilized eggs. In honey bees, parthenogenesis is common and here, drones develop as a result of parthenogenesis only. The mode of parthenogenesis is arrhenotoky in which only females are produced. Frog and sea urchin reproduces by artificial parthenogenesis.

Frogs reproduce by external fertilisation. The female frog ovulates in the water and releases its gametes. The sperm released from the male frog fertilizes to form zygote which turns into a well-developed egg. So, the correct answer is option B.

• The cerebral peduncles (also known as the cerebral crus) are the part of the midbrain that links the brainstem and the cerebrum of the brain. 
• They are the most anterior structure in the midbrain and contain the large ascending and descending tracts that run to and from the cerebrum. Hence, Cerebral peduncles connect the cerebrum of brain and brain stem.
So, the correct answer is 'Cerebral peduncles'.