Test: Reproduction in Organisms - 3 (Old NCERT) - Grade 12 MCQ

Each and every organism living on this earth can live only once as no one is immortal. There must be some process to maintain continuity.
Reproduction refers to the biological process of giving birth to their young ones similar to themselves. Reproduction is essential for living organisms in order to continue the species generation after generation. It maintains the variation present in a population and its inheritance.

The chain of yeast cells forms due to not separating of yeast cells after budding. When the yeast cells are not separated after budding, they form chain.

The process of combining the male gamete, or sperm, with the female gamete, or ovum. The product of fertilization is a cell called a zygote.

In Hydra, a bud begins to form on the tubular body of the parent. The bud then develops a mouth and tentacles and detaches from its parent. The new Hydra is fully developed and will find a substrate for its attachment. Thus the correct answer in option A.

The wall of the uterus has three layers of tissue. The external thin membranous perimetrium, middle thick layer of smooth muscle, myometrium and inner glandular layer called endometrium that lines the uterine cavity. The endometrium undergoes cyclical changes during menstrual cycle while the myometrium exhibits strong contractions during the delivery of the baby.

Parthenogenesis is a modification of sexual reproduction in which an egg develops into a complete organism without fertilization.
In honey bee, unfertilized eggs development to the mail b which are the drones with the haploid cell, and the fertilized egg give rise to the female Queen bees and worker bees with the diploid cell.
The Queen bee is the largest in size and lays a large number of eggs.
So, the correct option is 'Both Assertion and Reason are correct and Reason is the correct explanation for Assertion'

The asexual reproduction where the vegetative part of the plant which gives rise to a new plant is known as vegetative reproduction. Onion undergoes vegetative propagation by underground bulbs. It is an underground modified stem. It has a terminal bud which is enclosed by fleshy scales. Axillary buds occur at different places. The fleshy scales help in the storage of food. It has an adventitious root at the end. During vegetative propagation, the axillary and terminal buds grow into a new stem.

Morphogenetic movements during early embryo development result in the formation of different germ layers, which give rise to different tissues and organs in the body. Mocromeres are small cells that are located at the vegetal pole of the sea urchin embryo. They are responsible for giving rise to the ectoderm, which is one of the three primary germ layers.

During sea urchin development, the first cell division occurs along the animal-vegetal axis, creating two daughter cells - a larger macromere and a smaller micromere. The micromere undergoes further divisions and gives rise to additional micromeres, forming a cluster of cells called the micromere quartet. These micromeres then migrate to the vegetal pole, where they come in contact with the overlying macromeres.

The interaction between the micromeres and the macromeres triggers a series of signaling events and molecular interactions. The micromeres release signaling molecules, such as bone morphogenetic proteins (BMPs), which induce the adjacent macromeres to undergo a cell fate change. The macromeres start to express genes specific to the ectoderm lineage and acquire characteristics of ectodermal cells.

As a result, the macromeres differentiate into ectodermal cells, which will eventually give rise to various structures like the epidermis, nervous system, and sensory organs.

Buds do not germinate at very low temperature.

The four phases of the menstrual cycle are menstruation, the follicular phase, ovulation and the luteal phase. Common menstrual problems include heavy or painful periods and premenstrual syndrome (PMS). Knowing when in the menstrual cycle a woman is most likely to conceive can increase the chance of pregnancy.

• Reproduction is the process of producing new individuals of the same species from the pre-existing organism. The procreation of new offspring is obtained via sexual or asexual method. The particular species will disappear in time in the absence of reproduction. Thus, Reproduction is the only means to assure the survival of a species.
• During the process of reproduction, DNA passes from one generation to the next. It contains the replication process of DNA, the carrier of genetic information, and its transmission from parent to new individual. The replication of DNA takes place with consistency but with minor variations. This consistency leads to stability of species.
• The method of reproduction is responsible for providing stability to the population of species by giving birth to new individuals. The amount of birth rate must be at par with the rate of death to maintain the stability in the population of a species. By reproduction, organisms produce a large number of new individuals out of which several get perished and only some survive which ensures the continuity of species. These surviving organisms maintain a balance between the death ratios of naturally dying organisms. Therefore, it helps to replace the older population with the new population. Thus the population as a whole is not affected by reproduction and remains stable.
• Hence, Reproduction plays a major role in the inheritance of genetic characters which passed on from one generation to another and thereby it is inevitable to maintain the stability of species.

Amoeba is most commonly reproduced by the process of Binary fission.

The gamete formation in females is a cyclic activity that takes about 28/29 days and involves changes in the structure and function of the entire reproductive system. It is called a menstrual cycle.

Pollination is the characteristics of flowering plants i.e., angiosperms. After the pollen tube reaches the ovary, the process of double fertilization occurs in the angiosperms. One of the male gametes fuses with the egg cell (syngamy) which results in the formation of zygote. The second male gamete fuses with two polar nuclei to form a triploid, primary endosperm nucleus (PEN). This is called triple fusion. Since two fusion syngamy and triple fusion take place in an embryo sac, it is called double fertilisation. Central cell and PEN develop into the endosperm and zygote develops into the embryo.