Biology: CUET Mock Test - 1 - Class 12 MCQ

Clones are organisms with the same genetic and morphological similarities. It can be carried out naturally and artificially. Asexual reproduction is an example of natural cloning. Artificial cloning is carried out in labs. In biotechnology cloning can refer to DNA fragments or cell copies.

The fusion of a haploid male (23 chromosomes) and a haploid female gamete (23 chromosomes) produces a diploid (46 chromosomes) egg or a zygote. This process of reproduction is known as sexual reproduction.

Gametogenesis refers to the formation of the gametes. In sexual reproduction formation of gametes is very important since an offspring is formed only after the fusion of the gametes. Gamete transfer refers to bringing the 2 gametes together.

Sexual reproduction is divided into 3 events. Pre-fertilization, fertilization and post-fertilization events. Pre fertilization is the events occurring before fusion of gametes (gametogenesis), fertilization is the fusion of gametes to form zygote and post-fertilization are the events occurring after zygote formation.

Conidia are non-motile fungal spores that are produced singly or in chains by constriction of tips of conidiophores and are dispersed by wind. Zoospores are motile fungal spores. Gemmules are reproductive structures of sponges and nodes are just a site on the stem from where the new plant arises in rhizomes (vegetative propagation).

The phase when it is growing is known as the juvenile phase or the vegetative phase (in plants). The phase after that when the reproductive organs in the organism matures is known as the reproductive phase. Senescence is the phase when the plant starts deteriorating as it grows old and finally dies.

Water hyacinth

The water hyacinth, also known as Eichhornia crassipes, is referred to as the "terror of Bengal" because it is an invasive aquatic plant that has caused significant environmental and economic problems in Bengal and other regions. The plant grows and reproduces rapidly, covering the surface of water bodies, which negatively impacts native species, blocks sunlight and oxygen, and impedes water transportation. Efforts to control and remove water hyacinth have proven challenging and costly.

Organisms having haplontic lifecycles, zygote divides by meiosis to form haploid spores that grow into haploid individuals. Formation of zygote forms the vital link, ensuring continuity of the species.

It is difficult to clearly distinguish between the different phases in perennial plants. Some plants exhibit unusual flowering phenomena. Some plants flower every year, there are some that flower every 10 years and some plants flower every 50 years. Neelakurinji is a flowering plant that flowers every 12 years.

Male gamete is called antherozoid or sperm. They are called so in heterogametes. The two gametes produced are morphologically distinct types. The female gamete is called egg or ovum.

Embryogenesis is the process of embryo formation from a zygote. It undergoes mitosis and cell differentiation in this process. Cell differentiation helps in categorizing cells into specialized tissues.

Monocarpic plants flower only once in its lifetime. They die after flowering. Annuals like marigold, wheat, paddy, biennials like radish, perennials like Bambusa tulda which flowers every 50-100 years, fruits and dies.

Stamens are the male organs of a flower. Flowers maybe unisexual (either staminate or pistillate). In staminate plants only the male part, that is the stamen, is present and in the pistillate plants only the female part is present (ovaries). In bisexual plants, both are present.

Animals are categorized into 2 types of–oviparous and viviparous. Oviparous animals are those animals in which zygote development takes place outside the body. Reptiles and birds are examples of oviparous animals.

In suckers the lateral branches arise from basal and underground portions of the main stem. They grow horizontally underground and the leafy shots arise from the soil. For example, bananas.

 Polycarpic plants are those that flower repeatedly, which means they do not die after flowering once. Examples are perennials like apple, mango and perennial flowers like china rose, it flowers throughout the year.

A plant having both reproductive organs in the same plant is known as monoecious plants. It may also be known as homothallic conditions. Dioecious plants are those which have only one reproductive organ, also known as unisexual plants. Another word for dioecious plants is heterothallic.

Animals are categorized into 2 types of–oviparous and viviparous. Viviparous animals are those animals in which zygote development takes place within the body itself. Mammals are a very good example for viviparous reproduction.

Tulip is an example of a bulb. It is a vegetative propagation by underground stems. They have more than one terminal buds. Another very common example is the onion. Oxalis is and example of a runner and the other 2 are examples of vegetative propagation by leaves.

There are 3 phases in a life cycle.
(i) Juvenile phase/ vegetative phase: period from birth to maturation of reproductive systems.
(ii) Reproductive phase: period when the reproductive systems have matured and ready to produce offspring.
(iii) Senescence: period when the organism starts growing old and starts degrading.

Cockroach is an example of a unisexual organism, which means it can produce only one type of gamete, either male or female. Leech, tapeworm and earthworm are bisexual organisms, organisms that can produce both gametes.

The general term for the period of growth is known as juvenile phase. In plants it is known as the vegetative phase. The end of juvenile phase marks the beginning of reproductive phase.

Bulbils, also called vegetative propagation by flower buds is not an example of sub aerial vegetative propagation. It produces multicellular fleshy buds that give rise to new plants. Example, Agave.

Sexual reproduction is the fusion of the male and the female gamete that forms a single celled zygote, the process is known as fertilization. This process has been divided into 3 events. The pre-fertilization, fertilization and post-fertilization events.

 All heterogametic species can produce 2 types of gametes, male and female, their sex chromosomes are unidentical. Homogametic species the sex chromosomes are identical.

Since zygote development takes place inside the female body, they are in a protected environment. Unlike the oviparous animals, which are vulnerable. The chances of oviparous animals to survive is low.

Starfish reproduces by binary fission. Just like the single celled organisms, starfish breaks along the central axis. The 2 separate halves then lead an independent life by forming or regenerating the limbs and missing parts.

Hormones are chemical messengers that travel through the bloodstream (in case of animals). Hormones are responsible for the change in the phases in both plants and animals. Hormonal change can be affected by environmental factors too.

Meiocytes are cells in diploid organisms that undergo meiosis. Meiosis is the process of producing 4 haploid cells from a single cell that has been divided twice. The haploid cell then becomes diploid after its fusion with the other sex gamete.

In flowering plants, the zygote is formed in the ovule. The pollen tube is a mode of transportation for the pollens that lay on the stigma, to the ovaries. Anther consists of pollen grains (male gamete).