GK: Class 12 General Q&A · Page 151
3,658 free answers on GK (General) for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Why is the offspring formed by asexual reproduction referred to as a clone?
Offspring produced through asexual reproduction are called clones because they are genetically identical to their parent organism, possessing an exact replica of the parent's DNA. Since asexual reproduction involves only one parent and no fusion of gametes, there is no mixing of genetic material from two sources. The offspring receives a complete copy of the parent's genome through processes like mitosis (normal cell division), where DNA is duplicated precisely before the parent organism divi
- GeneralClass 12All
Which is a better mode of reproduction, asexual or sexual? Why?
Neither reproductive mode is inherently "better"—each offers distinct evolutionary advantages suited to different environmental contexts and survival strategies. Sexual reproduction excels in creating genetic diversity through the combination of genetic material from two parents, producing offspring with varied traits. This variation provides populations with resilience against diseases, parasites, and changing environmental conditions, as some individuals will likely possess traits adv
- GeneralClass 12All
How does zygote formation take place?
Zygote formation occurs through the process of fertilization, where a male gamete (sperm) fuses with a female gamete (egg or ovum) to combine their genetic material. In humans and most animals with internal fertilization, this typically happens in the fallopian tube when a sperm successfully penetrates the egg's outer protective layers. The sperm's acrosome releases enzymes that digest a path through the zona pellucida (egg coating), allowing the sperm head to contact the egg membrane. Once f
- GeneralClass 12All
Name two animals which show complete regeneration
Hydra and Planaria are two remarkable animals that demonstrate complete regeneration, meaning they can regrow entire organisms from small body fragments. Hydra, a tiny freshwater polyp, possesses such extraordinary regenerative abilities that it can be cut into several pieces, with each fragment developing into a complete new individual. Similarly, Planaria (flatworms) can regenerate a whole organism even if cut into multiple segments—a head piece will regrow a tail, while a tail piece
- GeneralClass 12All
Approximately how many sperms and ova are produced in human beings at a given time?
Human males produce sperms continuously and in enormous quantities—a healthy adult male generates approximately 200-300 million sperms per day, with each ejaculation containing between 200-500 million individual sperm cells. This massive overproduction occurs because the journey to fertilization is treacherous; of millions released, only a few hundred reach the vicinity of the egg, and typically only one successfully fertilizes it. This reproductive strategy compensates for the high att
- GeneralClass 12All
Name various parts of female reproductive system in human beings.
The female reproductive system in humans is a complex network of organs designed for gamete production, fertilization, and nurturing a developing baby. The primary structures include a pair of ovaries, which are oval-shaped organs that produce eggs (ova) and hormones like estrogen and progesterone. Each ovary connects to the uterus through a fallopian tube (oviduct), where fertilization typically occurs. The uterus is a muscular, pear-shaped organ with a thick inner lining called the endometr
- GeneralClass 12All
What are three main parts of a male gamete? Out of these three parts which part fuses with the female gamete to form the zygote?
A human sperm cell consists of three distinct structural parts: the head, middle piece (midpiece), and tail (flagellum). The head contains the nucleus with tightly packed genetic material (23 chromosomes) and is capped by an acrosome, a special enzyme-containing structure that helps penetrate the egg's protective layers. The middle piece is packed with mitochondria that generate ATP (energy) to power the sperm's movement. The tail is a long, whip-like flagellum that propels the sperm forward
- GeneralClass 12All
Name the gametes formed in the male reproductive system. Where are these gametes formed?
The male gametes are called spermatozoa or sperms, and they are produced in the testes through a specialized process called spermatogenesis. The testes contain numerous tightly coiled structures called seminiferous tubules, which serve as the actual sites of sperm formation. Within these tubules, specialized cells undergo meiotic division to produce millions of sperms daily, beginning at puberty and continuing throughout adult life. Sperm production requires a temperature slightly low
- GeneralClass 12All
Name the different parts of male reproductive system in man.
The male reproductive system in humans comprises several interconnected structures working together to produce, store, and deliver sperms. The primary organs include a pair of testes (singular: testis) housed in an external sac called the scrotum, which maintains optimal temperature for sperm production. Each testis connects to a coiled tube called the epididymis where sperms mature and are temporarily stored. From the epididymis, sperms travel through a muscular tube called the vas deferens
- GeneralClass 12All
In animals, whether male and female reproductive organs are present in the same organism or in different organisms?
In the animal kingdom, reproductive organ arrangement varies across species, with most animals being dioecious (having separate sexes) while some are hermaphroditic (possessing both male and female organs). The majority of familiar animals—including mammals, birds, most reptiles, and many insects—have distinct male and female individuals, each producing only one type of gamete. Males produce sperms in testes while females produce eggs in ovaries, and reproduction requires interact
- GeneralClass 12All
Name two essential components of sexual reproduction.
The two essential components of sexual reproduction are gametes (specialized reproductive cells) and fertilization (the fusion of these cells). Gametes include male sex cells called sperms or pollen and female sex cells called ova or eggs, each carrying half the genetic information needed to create a complete organism. Fertilization occurs when these two gametes unite, combining their genetic material to form a zygote with a full set of chromosomes, which then develops into a new individual.<
- GeneralClass 12All
In which type of reproduction the offspring generation is exactly similar to the parent?
Asexual reproduction produces offspring that are genetically identical to the parent organism, creating what scientists call clones. In this reproductive mode, a single parent organism generates new individuals without the involvement of gametes (sex cells) or fusion of genetic material from two parents. The offspring inherit an exact copy of the parent's DNA, resulting in zero genetic variation between parent and progeny under normal circumstances. This reproductive strategy occurs w
- GeneralClass 12All
Which process is essential in living organisms for the continuation of their species?
Reproduction is the essential biological process that ensures the continuation of species across generations. This fundamental life process allows organisms to produce new individuals of their own kind, maintaining genetic continuity and preventing extinction. Without reproduction, no species could persist beyond a single generation, making it as vital to species survival as nutrition and respiration are to individual survival. In the natural world, reproduction manifests in two prima
- GeneralClass 12All
What is National Park? Name any two National Parks of India. Where are these National Parks located?
A National Park is a strictly protected area designated by national governments to conserve pristine ecosystems, wildlife, and natural landscapes, where human exploitation and habitation are prohibited. These areas preserve representative or outstanding examples of natural environments, protecting endangered species and maintaining biodiversity while allowing regulated tourism and research activities. Unlike wildlife sanctuaries where some resource extraction may be permitted, National Parks
- GeneralClass 12All
What is meant by the migration of birds? Why do birds migrate?
Bird migration refers to the regular, seasonal movement of bird populations between breeding grounds and wintering areas, often covering thousands of kilometers across continents and hemispheres. This remarkable phenomenon involves predictable, large-scale journeys undertaken annually, typically between summer breeding habitats in higher latitudes (where abundant daylight and insect populations support raising chicks) and winter refuges in warmer regions (where food remains available year-rou
- GeneralClass 12All
What is the difference between zoo and wildlife sanctuaries?
Zoos and wildlife sanctuaries serve different conservation purposes and operate under fundamentally different principles regarding animal welfare and habitat management. Zoos are human-created facilities where animals are kept in confined, artificial enclosures primarily for public exhibition, education, research, and captive breeding of endangered species. Animals in zoos live in designed habitats that attempt to mimic natural environments but remain limited in size—these creatures dep
- GeneralClass 12All
What are the causes and consequences of deforestation?
The causes of deforestation are complex and interconnected, driven primarily by human economic activities and population pressures. Agricultural expansion remains the dominant cause globally—forests are cleared to create farmland for growing commercial crops like palm oil, soybeans, coffee, cocoa, and rubber, or converted to pastures for cattle ranching, particularly in tropical regions. Commercial logging for timber, paper, and wood products drives extensive forest cutting, often openi
- GeneralClass 12All
Which structure is called as little nucleus? What is the role of this structure?
The nucleolus (plural: nucleoli) is often called the "little nucleus" because it appears as a dense, spherical structure within the nucleus. Despite its small size, the nucleolus is not surrounded by its own membrane and is actually a specialized region within the nucleus where specific genetic activity occurs. It is clearly visible under a microscope as a darker spot inside the nucleus of most eukaryotic cells. The primary role of the nucleolus is the synthesis and assembly of riboso
- GeneralClass 12All
State three differences between a plant cell and an animal cell.
Plant and animal cells, while sharing the basic eukaryotic organization, exhibit three major structural differences reflecting their distinct lifestyles. First, plant cells possess a rigid cell wall composed of cellulose outside the plasma membrane, while animal cells have only a flexible plasma membrane. This cell wall provides structural support and protection, allowing plants to grow tall without a skeletal system and maintaining cell shape under varying water pressures. Animal cells lack
- GeneralClass 12All
Draw the general diagram of a plant cell and label it.
While I cannot create visual diagrams directly, I can guide you on how to draw and properly label a plant cell diagram for your biology studies. A well-drawn plant cell should be roughly rectangular or box-shaped to represent the rigid cell wall, unlike the more flexible, rounded shape of animal cells. Begin by drawing the outer boundary as a thick double line representing the cell wall, then draw another line just inside it for the plasma membrane. Inside the cell, position a large c