Q.How are malignant tumours different from benign tumours ? Why are some patients treated with -interferons ?
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🔒 Start your 14-day free trial to unlock the full solution →Part (a)Concept understanding — Cancer Cell Biology
Imagine a city where every cell is a citizen with a specific job. Skin cells form the outer wall, stomach cells digest food, nerve cells carry messages. Each citizen follows a strict rulebook: grow when needed, stop when the job is done, and eventually die to make room for younger replacements. This orderly cycle is what keeps the city healthy.
Now, what happens if one citizen suddenly stops listening to the rules? It starts growing uncontrollably, refuses to die, and begins crowding out its neighbours. Worse, it might break through the city walls and travel to a different district, setting up a new colony there. That rogue citizen is a cancer cell. Cancer cell biology is the study of how normal, well-behaved cells turn into these rebellious, destructive ones.
The core idea: a breakdown of cellular discipline
Every cell in your body contains a complete set of instructions — your DNA. Think of DNA as the city's master blueprint and rulebook. Inside that blueprint are specific genes that act like traffic lights: some tell the cell to grow (these are called proto-oncogenes), and others tell it to stop growing or to self-destruct when damaged (these are called tumour suppressor genes).
Cancer begins when these traffic lights break. A proto-oncogene might get stuck on green, so the cell grows non-stop. Or a tumour suppressor gene might get stuck on red, so the cell never gets the signal to stop or die. Usually, a single broken light isn't enough — the cell has backup systems. But over years, multiple lights break, and the cell loses all control.
Cancer is not one disease but a collection of diseases. All cancers share one fundamental property: uncontrolled cell division caused by accumulated damage to the DNA. The type of cancer depends on which original cell type went rogue (e.g., lung cells → lung cancer, skin cells → skin cancer).
How a normal cell becomes cancerous: a step-by-step intuition
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Initiation — A cell's DNA gets damaged by something (a chemical in cigarette smoke, UV radiation from the sun, a random copying error during cell division). This damage is a mutation. One mutation alone rarely causes cancer, but it's the first crack in the rulebook.
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Promotion — The damaged cell is now slightly more prone to grow. If it encounters more damaging agents (promoters), it accumulates more mutations. Each mutation pushes it further from normal behaviour.
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Progression — After several mutations, the cell now divides rapidly, ignores signals to stop, and refuses to die. It forms a mass of cells called a tumour. Not all tumours are cancerous — benign tumours stay in one place and don't invade neighbours. Malignant tumours are the dangerous ones: they invade nearby tissues and can break off to travel through blood or lymph vessels.
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Metastasis — This is the most dangerous step. A few cancer cells detach from the original tumour, travel through the bloodstream or lymphatic system, and settle in a distant organ (like the liver, lungs, or brain). There, they start a new tumour. This spread is what makes cancer so hard to treat.
Why does this matter for you?
You don't need to memorise gene names or pathways. What matters is understanding the logic behind prevention and treatment:
- Prevention works because most cancers take years to develop. Avoiding known DNA-damaging agents (tobacco, excessive sun, certain viruses like HPV) reduces the chance of those first mutations.
- Early detection works because a small, localised tumour can often be surgically removed before it metastasises. …
Part (b)Concept understanding — Assisted Reproductive Technology
Imagine you have a friend who wants to have a baby, but nature isn't cooperating. Maybe the fallopian tubes are blocked, or the sperm count is very low, or the woman's age makes it difficult. For decades, that was the end of the story. But today, doctors have a toolkit of medical procedures that can step in and help — that toolkit is called Assisted Reproductive Technology, or ART.
At its simplest, ART is any medical technique that handles a human egg or sperm outside the body to help a person get pregnant. The most famous example is IVF (in vitro fertilisation), where the egg and sperm are combined in a lab dish — "in vitro" means "in glass" — and the resulting embryo is then placed into the woman's uterus. But ART is broader than just IVF. It includes everything from injecting a single sperm directly into an egg (ICSI) to using a donor's egg or sperm, or even having another woman carry the pregnancy (surrogacy).
The NCERT textbook (Class 12 Biology, Chapter 4) defines ART as all techniques that involve the direct handling of gametes (sperm and eggs) or embryos outside the body to achieve pregnancy. This is the key distinction: if the procedure doesn't involve handling eggs, sperm, or embryos in a lab, it's not ART.
Why does this matter for a commerce or humanities student? Because ART is not just a medical story — it's a social, legal, and economic one. It raises questions about who can afford it (it's expensive), who gets to be a parent (single people, same-sex couples), and what happens to unused embryos (legal and ethical debates). In India, the Assisted Reproductive Technology (Regulation) Act, 2021 now governs these procedures, requiring clinics to be registered and banning commercial surrogacy for foreigners. So when you read about "test-tube babies" or "surrogacy laws" in the news, you're looking at ART in action.
Here are the main techniques you should know, as listed in the NCERT:
- IVF (In Vitro Fertilisation): Egg and sperm are mixed in a lab dish. The embryo is then transferred to the uterus.
- ICSI (Intracytoplasmic Sperm Injection): A single sperm is injected directly into an egg. Used when sperm count is very low.
- GIFT (Gamete Intrafallopian Transfer): Eggs and sperm are placed directly into the fallopian tube, so fertilisation happens inside the body.
- ZIFT (Zygote Intrafallopian Transfer): A fertilised egg (zygote) is placed into the fallopian tube. …
Part (a)
Benign tumours stay localised (remain confined to their original site), are usually encapsulated, and do not spread. Malignant tumours grow rapidly, invade surrounding tissues, and their cells metastasise — sloughing off, travelling via blood/lymph, and forming new (secondary) tumours elsewhere; they are life-threatening. …
Part (a): Malignant tumours invade tissues and metastasise while benign tumours stay localised; alpha-interferons are given to activate the immune system against cancer cells.
Part (b): In MOET, a FSH-like gonadotrophin is given to the cow to induce superovulation, so it releases many eggs in one cycle for embryo transfer.
Part (a)
Malignant vs benign tumours
| Feature | Benign tumour | Malignant tumour |
|---|---|---|
| Growth | Slow, limited | Rapid, uncontrolled |
| Spread | Remains localised, usually encapsulated | Invades neighbouring tissues |
| Metastasis | Absent | Present — cells reach distant sites via blood/lymph and form secondary tumours |
| Danger | Generally not life-threatening | Life-threatening |
The key difference is that malignant (cancerous) cells lose the property of contact inhibition, invade surrounding tissue, and metastasise — the most dangerous property, because cells spread through the blood/lymph and start new tumours at distant sites.
Why alpha-interferons? …
Showing the 12 most recent of 38 on this concept.
- CBSE 2026Set A1 markMCQQ.What is it called when an embryo having more than eight blastomeres is transferred to the uterus for development?(a) IVF(b) Intrauterine Transfer(c) Zygote Intra-fallopian Transfer(d) ICSI
›Reveal solutionSolution
An embryo with more than 8 blastomeres is placed in the uterus by Intrauterine Transfer (IUT); an early embryo (up to 8 blastomeres) goes into the fallopian tube (ZIFT).
In assisted reproductive technologies, embryos produced in the laboratory are transferred into the female. If the embryo is at an early stage — up to the 8-blastomere stage — it is transferred into the fallopian tube by Zygote Intra-Fallopian Transfer (ZIFT). If the embryo has more than 8 blastomeres, it is transferr …
- CBSE 2026Set ZOOLOGY1 markMCQQ.In the assisted reproductive technique, GIFT, the collected sperm and egg are transferred to which organ of the female?(a) Uterus(b) Vagina(c) Urethra(d) Fallopian tube
›Reveal solutionSolution
GIFT stands for Gamete Intra-Fallopian Transfer - collected sperm and egg are transferred into the fallopian tube.
GIFT is an Assisted Reproductive Technology (ART) used to help couples who cannot conceive naturally, especially those with a healthy uterus but who cannot produce an ovum (e.g., due to ovarian issues). In this technique, an ovum from a donor female is collected and transferred, along with the sperm, into the fallopian tube (oviduct) of the recipi …
- CBSE 2026Set ANNUAL1 markMCQQ.The technique by which sperm is directly injected into the ovum, is(a) ZIFT(b) GIFT(c) ZIUT(d) ICSI
›Reveal solutionSolution
ICSI is an assisted reproductive technique where a sperm is directly injected into an ovum's cytoplasm, bypassing the need for natural sperm penetration.
Among assisted reproductive technologies (ART):
- ZIFT (Zygote Intra-Fallopian Transfer) transfers an early embryo/zygote formed in the lab into the fallopian tube.
- GIFT (Gamete Intra-Fallopian Transfer) transfers an ovum collected from a donor into the fallopian tube of another female who cannot produce her own ova. …
- CBSE 2026Set ANNUAL1 markMCQQ.Contact inhibition is a property related to(a) Normal cells(b) Cancerous cells(c) Hepatic cells(d) Macrophages
›Reveal solutionSolution
Contact inhibition means normal cells stop dividing and moving once they come into contact with neighbouring cells; cancer cells characteristically lose this property.
Normal cells show contact inhibition — when growing in a culture or tissue, a normal cell stops proliferating and migrating once it touches surrounding cells, which keeps tissue growth orderly and confined.
…
- CBSE 2026Set ANNUAL1 markQ.Case Study - 1. Read the passage given below and answer the following questions : In case of an infertile couple male has abnormally low sperm count in ejaculation and female has blocked oviduct & has spermicidal secretions in vagina but can provide suitable environment for development of embryo. What is infertility ?
›Reveal solutionSolution
Infertility is diagnosed when a couple fails to achieve conception/pregnancy despite regular unprotected sex over an extended period, and can arise from a defect/deficiency in either partner.
Infertility is defined as the inability of a couple to produce/conceive a child even after normal, unprotected sexual cohabitation for a reasonable period of time (typically taken as one year or more of regular attempts). Its causes can be physical, congenital, disease-related, drug/immunological or even purely psychological, and may lie with either the male partner (e.g. low sperm count, blocked ducts), the female partner (e.g. blocked oviducts, hormonal issues), or both. In cases such as the one described here — a male with an abnormally low sperm count and a …
- CBSE 2026Set ANNUAL1 markQ.Refer to the Case Study - 1 passage above (infertile couple with low sperm count and blocked oviduct with spermicidal vaginal secretions). Suggest ART used in above case.
›Reveal solutionSolution
Since the female's oviduct is blocked (preventing normal gamete transport and fertilisation in vivo) but her uterus can support an embryo, and the male has a low sperm count, the couple needs fertilisation to happen OUTSIDE the body, followed by placing the resulting embryo directly into the uterus (or an unblocked part of the oviduct).
Given that (i) the female partner has a blocked oviduct — meaning sperm and egg cannot naturally meet or the fertilised egg cannot travel down to the uterus — but her uterus can support embryonic development, and (ii) the male partner has a low sperm count, the appropriate ART is:
- IVF (In Vitro Fertilisation): ova collected from the female and sperm from the male are made to fuse in the laboratory ('test tube baby' technique) — this fertilisation step does not require an unblocked oviduct.
- ICSI (Intracytoplasmic Sperm Injection): used alongside IVF because of the male's low sperm count, a single healthy sperm is directly injected into the ovum to ensure fertilisation. …
- CBSE 2026Set ANNUAL1 markQ.Name one substance which is used for cancer immunotherapy.
›Reveal solutionSolution
Interferons, natural antiviral signalling proteins, are also used therapeutically to stimulate the immune system against cancer.
Interferons are proteins naturally secreted by virus-infected cells to help protect neighbouring, uninfected cells from viral infection, but they also have immune-modulating properties that make them useful in cancer immunotherapy — recombinant interferons are used clinically to stimulate the patient's immune system to more effectively recognise and destroy cancer cells (e.g., in the treatment of certain leuk …
- CBSE 2025Set 57/6/11 markMCQQ.A characteristic property that distinguishes a malignant tumor from a benign tumor is : (A) Metamorphosis (B) Metastasis (C) Metabolism (D) Metagenesis
›Reveal solutionSolution
Metastasis — the ability to invade surrounding tissues and spread to distant body sites — is the defining characteristic that separates malignant tumors from benign ones.
When we talk about tumors, we're really talking about two fundamentally different kinds of abnormal cell growth. Both benign and malignant tumors arise from uncontrolled cell division, but what happens next determines whether a tumor remains a localized nuisance or becomes a life-threatening disease.
Benign tumors are, in a sense, well-behaved troublemakers. They grow slowly, remain confined within a capsule of connective tissue, and stay exactly where they started. A benign tumor in your liver stays in your liver. It might press on nearby structures and cause problems through sheer size, but it doesn't invade the surrounding tissue or send rogue cells traveling through your body. Surgical removal usually cures the problem completely because the tumor has clear boundaries.
Malignant tumors — cancers — are an entirely different story. The cells in a malignant tumor lose the normal restraints that keep cells in their proper place. They acquire the ability to break through the basement membrane that normally acts as a barrier, invade neighboring tissues, and most critically, enter the bloodstream or lymphatic system. Once in circulation, these cancer cells can establish secondary tumors at distant sites. A lung cancer cell might travel to the brain, bone, or liver and start a new colony there. This process of spreading from the original site to distant organs is called metastasis, and it's the hallmark of malignancy.
ImportantMetastasis is not just spreading — it's a multi-step process requiring cancer cells to detach, survive in circulation, invade new tissue, and establish growth at a distant site. Benign tumors never metastasize. …
- CBSE 2025Set X11 markMCQQ.Which one among the following ART can be used to rectify if the infertility is due to low sperm count?(a) GIFT(b) IUT(c) ZIFT(d) IUI
›Reveal solutionSolution
Intra-uterine insemination (IUI) is used to overcome infertility due to low sperm count.
In IUI, semen collected either from the husband or a healthy donor is artificially introduced into the uterus of the female. It is the assisted reproductive technology specifically recommended when the male partner is unable to inseminate the female or has a very low sperm count. GIFT transfers an ovum/gamete into the fallopian tube of a female who …
- CBSE 2025Set KH1 markQ.Write the full form of abbreviation I.V.F.
›Reveal solutionSolution
I.V.F. = In Vitro Fertilisation — fertilisation done outside the body in the lab.
Concept. In IVF, ova collected from the female and sperm from the male are combined in vitro (literally 'in glass', i.e. in a laboratory dish). The resulting zygote/early embryo is then transferred back — an embryo up to the 8-blastomere stage is placed in the fallopian tube (ZIFT) and later stages into the uterus (IU …
- CBSE 2025Set F1 markMCQQ.By which of the following methods do cancer cells divide?(a) Mitosis(b) Amitosis(c) Meiosis(d) None of these
›Reveal solutionSolution
Cancer cells multiply by uncontrolled mitosis.
Cancer arises when normal cells lose the control over cell division (contact inhibition and cell-cycle checkpoints). Such transformed cells proliferate rapidly and continuously by mitosis, forming a mass called a tumour. This uncontrolled mitotic division and the ability to invade other tissues (metastasis) ar …
- CBSE 2025Set F1 markMCQQ.At which of the following stages is the embryo transferred to fallopian tube?(a) 8-celled embryo(b) 32-celled embryo(c) Zygote(d) Zygote or 8-celled embryo
›Reveal solutionSolution
Assisted transfer into the fallopian tube uses a zygote or an early embryo up to the 8-celled stage (ZIFT).
Among assisted reproductive technologies, in ZIFT (Zygote Intra Fallopian Transfer) the zygote or an early cleaving embryo with up to 8 blastomeres is introduced into the fallopian tube. (An embryo of more than 8 blastomeres is instead transferred into the uterus — IUT …
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