General Q&A for Class 12 · Page 227
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
What are the biological needs of an adolescent?
Adolescents have increased biological needs to support their rapid growth and development during puberty. Nutritionally, they require higher caloric intake, adequate protein for tissue building, calcium and vitamin D for bone growth, iron (especially for menstruating girls), and a balanced mix of carbohydrates, fats, vitamins, and minerals. The growth spurt during adolescence demands more energy and nutrients than at almost any other life stage except infancy. Beyond nutrition, adoles
- GeneralClass 12All
How is the sex of the baby determined?
The sex of a baby is determined genetically at conception through the combination of sex chromosomes from both parents. Every human cell contains 23 pairs of chromosomes, with the 23rd pair being the sex chromosomes that determine biological sex. Females have two X chromosomes (XX configuration), while males have one X and one Y chromosome (XY configuration). When reproductive cells (gametes) form, they undergo meiosis and receive only one chromosome from each pair. Therefore, all egg
- GeneralClass 12All
State the role of hormones in initiating reproductive function.
Hormones play the central role in initiating and regulating reproductive function during puberty and throughout reproductive life. The process begins when the hypothalamus in the brain starts releasing gonadotropin-releasing hormone (GnRH), which signals the pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones then stimulate the gonads—testes in males and ovaries in females—to produce sex hormones and begin reproductive process
- GeneralClass 12All
Write the function of adrenaline hormone.
Adrenaline, also known as epinephrine, is a hormone secreted by the adrenal glands (located above the kidneys) that prepares the body for "fight or flight" responses during stressful or emergency situations. When you encounter danger, stress, or excitement, adrenaline is rapidly released into the bloodstream, triggering immediate physiological changes that enhance your ability to respond quickly and effectively. The primary functions of adrenaline include increasing heart rate and blo
- GeneralClass 12All
Write a short note on balanced diet.
A balanced diet contains appropriate proportions of all essential nutrients needed to maintain health, support growth, and provide energy for daily activities. It should include carbohydrates (for energy), proteins (for growth and repair), fats (for energy storage and vitamin absorption), vitamins, minerals, and adequate water. The key principle is variety and moderation—no single food provides all necessary nutrients, so eating diverse foods from different food groups ensures comprehen
- GeneralClass 12All
Explain 'Goitre'.
Goitre is an abnormal enlargement of the thyroid gland, appearing as a visible swelling at the front of the neck. The most common cause is iodine deficiency, which prevents the thyroid from producing adequate amounts of thyroid hormones (thyroxine and triiodothyronine). When these hormone levels drop, the pituitary gland responds by releasing more thyroid-stimulating hormone (TSH), causing the thyroid gland to enlarge as it attempts to compensate for the deficiency. Iodine is an essen
- GeneralClass 12All
How does endocrine glands function?
Endocrine glands function by producing and secreting hormones directly into the bloodstream rather than through ducts. These ductless glands act as the body's chemical communication system, releasing hormones in response to specific signals from the nervous system, other hormones, or changes in blood composition. Once released, hormones circulate through the blood until they reach their target organs or tissues, where they bind to specific receptors and trigger cellular responses. The
- GeneralClass 12All
Why is the pelvis of a female wider than that of a male?
The female pelvis is wider than the male pelvis primarily to accommodate childbirth. This wider structure, which develops fully during puberty under the influence of estrogen, creates a larger pelvic inlet and outlet through which a baby can pass during delivery. The broader shape, along with a more circular pelvic cavity, provides the necessary space for a baby's head and body to navigate the birth canal. Beyond just width, the female pelvis has several other adaptations for reproduc
- GeneralClass 12All
. A nine year old boy is 120 cm tall. If the present height of the boy is 75% of his full height, calculate the full height which the boy will eventually reach at the end of growth period.
To calculate the boy's eventual full height, we need to determine what 100% would be if 120 cm represents 75%. Using basic proportion: if 75% = 120 cm, then 1% = 120 ÷ 75 = 1.6 cm. Therefore, 100% = 1.6 × 100 = 160 cm. Alternatively, you can use the formula: Full height = (Current height ÷ Current percentage) × 100 = (120 ÷ 75) × 100 = 160 cm. This calculation suggests the boy will reach approximately 160 cm (or 5 feet 3 inches) at full adult hei
- GeneralClass 12All
Explain how sex is determined in the unborn baby.
Sex determination in an unborn baby occurs at the moment of fertilization and depends on which sex chromosome is carried by the sperm that fertilizes the egg. Human cells normally contain 23 pairs of chromosomes, with the 23rd pair being the sex chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The mother's egg always contributes an X chromosome, since that's all she has to give. The father's sperm, however, can carry either an X or a
- GeneralClass 12All
What are the developmental changes in females at the age of 13?
At age 13, girls typically experience several significant developmental changes as they progress through puberty. The most noticeable physical changes include breast development, widening of hips and pelvis, growth spurts that increase height rapidly, and the beginning or continuation of menstruation (menarche). Body hair appears in new areas including the underarms and pubic region, and the skin may become oilier due to increased sebaceous gland activity. Beyond physical changes, hor
- GeneralClass 12All
Name the hormone which brings about metamorphosis in silk moth and changes caterpillar (larva) into adult silk moth.
The hormone responsible for metamorphosis in silk moths is ecdysone, also known as the molting hormone. This steroid hormone triggers the transformation of the caterpillar (larva) through the pupal stage and ultimately into the adult silk moth. Ecdysone works in coordination with another hormone called juvenile hormone, which must decrease for metamorphosis to proceed properly. During metamorphosis, ecdysone initiates dramatic cellular changes including the breakdown of larval tissues
- GeneralClass 12All
What are secondary sexual characters?
Secondary sexual characteristics are the physical features that distinguish males from females but are not directly involved in reproduction itself. These characteristics develop during puberty under the influence of sex hormones and help differentiate the two sexes beyond their primary reproductive organs. Unlike primary sexual characteristics (the reproductive organs present from birth), secondary characteristics emerge during adolescence. In males, these include facial and body hai
- GeneralClass 12All
Name both the male and female hormones.
The primary male hormones are androgens, with testosterone being the most important one, produced mainly by the testes. The primary female hormones are estrogen and progesterone, produced primarily by the ovaries. However, it's important to understand that both males and females produce all these hormones, just in different proportions—men produce small amounts of estrogen, and women produce small amounts of testosterone. Testosterone is responsible for the development of male s
- GeneralClass 12All
3. State one situation (other than menopause) when ovulation and menstruation stop in a woman.
Pregnancy is the most common situation when both ovulation and menstruation temporarily stop in a woman. Once conception occurs, hormonal changes—particularly elevated levels of progesterone and human chorionic gonadotropin (hCG)—prevent the ovaries from releasing additional eggs and halt the menstrual cycle. This natural pause continues throughout the pregnancy and typically extends into the breastfeeding period. The absence of menstruation during pregnancy, known as phys
- GeneralClass 12All
Name the gland which secretes insulin hormone.
The pancreas is the gland that secretes insulin hormone. More specifically, specialized clusters of cells within the pancreas called the islets of Langerhans (or pancreatic islets) produce this crucial hormone. Within these islets, beta cells are responsible for synthesizing and releasing insulin in response to elevated blood glucose levels. Insulin plays a vital role in regulating blood sugar by enabling cells throughout the body to absorb glucose from the bloodstream and use it for
- GeneralClass 12All
. Which comes earlier in the life of woman: menarche or menopause?
Menarche comes much earlier in a woman's life than menopause. Menarche refers to the first menstrual period, which typically occurs between ages 10-16, with the average age being around 12-13 years. This marks the beginning of reproductive capability and is one of the key indicators that puberty has begun. Menopause, in contrast, occurs much later, usually between ages 45-55, marking the end of a woman's reproductive years. During menopause, menstrual periods permanently stop, and the
- GeneralClass 12All
1. What term is used for the secretions of endocrine glands?
The secretions of endocrine glands are called hormones. These chemical messengers are released directly into the bloodstream and travel throughout the body to reach specific target organs or tissues. Unlike exocrine glands that release their secretions through ducts, endocrine glands are ductless and rely on the circulatory system to transport hormones to where they're needed. Hormones regulate a wide range of bodily functions including growth, metabolism, reproduction, mood, and slee
- GeneralClass 12All
How does a Hydra reproduce? Explain with the help of labeled diagrams.
Hydra reproduces primarily through asexual budding when environmental conditions are favorable, though it can also reproduce sexually under stress conditions. During asexual reproduction, a small outgrowth or bud emerges from the parent Hydra's body wall, typically in the middle region of the organism. This bud initially appears as a small protrusion of the body column, containing extensions of both the outer ectoderm and inner endoderm layers along with the central gastrovascular cavity. As
- GeneralClass 12All
Define the term ovulation and implantation.
. Ovulation is the process by which a mature egg (ovum) is released from the ovary into the fallopian tube, typically occurring approximately midway through the menstrual cycle in human females (around day 14 of a 28-day cycle). This release is triggered by a surge in luteinizing hormone (LH) secreted by the pituitary gland, which causes the mature follicle housing the egg to rupture and expel the ovum. The released egg is swept into the fallopian tube by finger-lik