UP Board Class 12 Biology Question Paper 2024 (Code 348 GJ) Available- Download Solution PDF

Uracil is found in RNA instead of thymine. In DNA, the four nitrogenous bases are adenine (A), thymine (T), cytosine (C), and guanine (G). Quick Tip: Remember: DNA contains thymine (T), while RNA contains uracil (U) in place of thymine.

Mendel studied seven contrasting traits in pea plants, including seed shape, seed color, flower color, flower position, pod shape, pod color, and plant height. Quick Tip: Remember: Mendel studied 7 traits in pea plants, including height, color, and shape of seeds and pods.

Sickle cell anemia is caused by a point mutation in the beta-globin gene, where a single nucleotide substitution (adenine to thymine) results in the production of abnormal hemoglobin. Quick Tip: Remember: Sickle cell anemia results from a point mutation, where a single DNA base change alters hemoglobin structure.

Pollen grains are produced in the microsporangium, which is located inside the anther of the stamen in a flower. The microspore mother cells undergo meiosis to form haploid pollen grains. Quick Tip: Remember: Pollen grains develop inside the microsporangium, which is part of the stamen.

Malaria is caused by the Plasmodium parasite, which is transmitted to humans through the bite of an infected female Anopheles mosquito. Quick Tip: Remember: Malaria is transmitted by the female Anopheles mosquito, which carries the Plasmodium parasite.

PCR is a widely used technique in molecular biology for amplifying small segments of DNA. It allows researchers to produce millions or billions of copies of a specific DNA sequence in a short period of time, making it invaluable for applications such as genetic research, medical diagnostics, forensic analysis, and biotechnology. Quick Tip: Remember: PCR stands for Polymerase Chain Reaction and is used for amplifying DNA sequences.

Dolly was the first transgenic sheep produced using somatic cell nuclear transfer (SCNT), demonstrating the feasibility of cloning in mammals. Quick Tip: Remember: Dolly the sheep was the first cloned transgenic animal using SCNT technology.

Brightly colored corollas attract insects such as bees and butterflies, which aid in pollination by transferring pollen from one flower to another. Quick Tip: Remember: Bright-colored flowers attract insects for pollination; this is called entomophily.

Green plants are called producers because they synthesize their own food through photosynthesis using sunlight, carbon dioxide, and water. Quick Tip: Remember: Green plants are called producers as they make food through photosynthesis.

Decomposition is the process by which complex organic matter is broken down into simpler substances by decomposers such as bacteria and fungi.
Decomposition plays a vital role in nutrient cycling by converting organic matter into inorganic nutrients, making them available for plant uptake. Quick Tip: Remember: Decomposers like bacteria and fungi break down dead matter to recycle nutrients in the ecosystem.

Two examples of fermented beverages are:

(A) Wine
(B) Beer


Fermented beverages are produced by microbial fermentation of carbohydrates present in fruits or grains, primarily using yeast. Quick Tip: Remember: Wine is made from fermented grapes, while beer is made from fermented barley.

The test tube baby programme refers to In Vitro Fertilization (IVF), where fertilization occurs outside the female body in a laboratory.In IVF, an egg is fertilized by ***** in a lab, and the resulting embryo is implanted into the woman's uterus. This technique is used to assist couples facing infertility issues. Quick Tip: Remember: IVF helps infertile couples by fertilizing the egg outside the body and implanting it in the uterus.

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Quick Tip: Remember: Homozygous means identical alleles; heterozygous means different alleles.

Two important functions of ribosomes are:

(A) Synthesis of proteins by translating mRNA sequences.
(B) Facilitating the assembly of amino acids into polypeptides.

Ribosomes act as the site of protein synthesis by reading the genetic information carried by mRNA and assembling amino acids in the correct sequence. Quick Tip: Remember: Ribosomes help in protein synthesis and amino acid assembly, essential for cell function.

Polyembryony is the phenomenon of the development of multiple embryos within a single seed. It can occur naturally in certain plant species such as citrus and mango, as well as in some animals like armadillos.
Polyembryony can be of three types:

(A) Simple Polyembryony: Occurs due to the cleavage of the zygote.
(B) Multiple Polyembryony: Due to the presence of multiple embryo sacs in an ovule.
(C) Adventive Polyembryony: When embryos arise from somatic cells outside the embryo sac. Quick Tip: Remember: Polyembryony results in multiple embryos in a single seed; common in citrus fruits.

The gynoecium consists of three main parts:

(A) Stigma: The receptive surface for pollen grains.
(B) Style: The slender stalk that connects stigma to ovary.
(C) Ovary: Contains ovules which develop into seeds after fertilization.


Diagram:

Quick Tip: Remember: Gynoecium consists of stigma (pollen reception), style (connective stalk), and ovary (contains ovules).

The three accessory glands of the male reproductive system are:


Seminal Vesicles

These glands produce a significant portion of the fluid that makes up *****. The secretion is rich in fructose, which provides energy for *****, and other substances like prostaglandins that aid in ***** motility and viability.
Prostate Gland

The prostate gland secretes a milky, alkaline fluid that helps neutralize the acidic environment of the female reproductive tract, enhancing ***** survival and motility.
Bulbourethral Glands (Cowper's Glands)

These are small glands located below the prostate. They secrete a clear, viscous fluid that lubricates the urethra and neutralizes any residual acidity, preparing the pathway for ***** during ejaculation.

These accessory glands work together to produce and support the transport of *****, ensuring the survival and functionality of *****.
Quick Tip: Remember: Male accessory glands include seminal vesicles (nutrients), prostate gland (enzymes), and Cowper’s gland (lubrication).

Quick Tip: Remember: Primary productivity = plants (photosynthesis); Secondary productivity = consumers (energy transfer).

Natural selection is the process by which organisms with favorable traits are more likely to survive and reproduce, passing those traits to the next generation.

Example:

The classic example of natural selection is the evolution of the peppered moth (Biston betularia) in industrial areas. During the Industrial Revolution, darker moths had a survival advantage as they were better camouflaged against soot-darkened trees, leading to an increase in their population. Quick Tip: Remember: Natural selection leads to survival of the fittest; an example is the peppered moth adapting to pollution.

Restriction enzymes, also known as molecular scissors, cut DNA at specific recognition sites.

Functions:

(A) They cut DNA at specific sequences called restriction sites, producing sticky or blunt ends.
(B) Used in genetic engineering for cloning, gene splicing, and DNA analysis. Quick Tip: Remember: Restriction enzymes cut DNA at specific sites; commonly used in genetic engineering.

Adaptive radiation is the evolutionary process where organisms diversify rapidly into multiple new forms to adapt to different environmental conditions.

Example:

Darwin’s finches in the Galápagos Islands evolved different types of beaks suited to their feeding habits, demonstrating adaptive radiation. Quick Tip: Remember: Adaptive radiation = evolution of diverse forms from a common ancestor; e.g., Darwin's finches.

Parthenocarpic fruits are fruits that develop without the process of fertilization or seed formation. These fruits are typically seedless, making them desirable for commercial purposes and consumption. The phenomenon of parthenocarpy occurs naturally in some plant species or can be induced artificially through various techniques.


Examples: Banana, seedless grapes.

Importance:

Beneficial in commercial fruit production.
Enhances fruit quality and shelf life. Quick Tip: Remember: Parthenocarpic fruits develop without fertilization and are seedless, e.g., banana and seedless grapes.

Divergent evolution refers to the process by which two or more related species evolve different traits or characteristics due to adaptation to different environments or ecological niches. This occurs when a common ancestor splits into multiple descendant species, each evolving unique features as they adapt to their specific habitats or lifestyles. Over time, these differences can lead to significant diversity among species that share a common origin.


Example:

The forelimbs of mammals such as bats, whales, and humans share a common ancestral structure but have evolved different functions like flying, swimming, and grasping. Quick Tip: Remember: Divergent evolution leads to different traits in related species due to different environments; e.g., forelimbs in mammals.

Transfer RNA (t-RNA) is a type of RNA that helps in the translation process by bringing specific amino acids to the ribosome during protein synthesis.t-RNA (Transfer RNA) is a crucial molecule in the process of protein synthesis, acting as an adapter that translates the genetic code carried by mRNA into the corresponding amino acids. It plays a vital role in the translation phase of protein synthesis, ensuring that the correct amino acids are added to the growing polypeptide chain.



Functions of t-RNA:

Carries amino acids to the ribosome for protein synthesis.
Recognizes the mRNA codon using its anticodon region. Quick Tip: Remember: t-RNA carries amino acids to ribosomes and helps decode mRNA during protein synthesis.

Opioid drugs are a class of substances that act on opioid receptors in the brain and nervous system to produce analgesic (pain-relieving) effects. They mimic the action of endorphins, which are natural chemicals in the body that reduce pain and promote feelings of well-being. While opioids are highly effective for pain management, they also carry a high risk of addiction, dependence, and overdose due to their psychoactive properties.
Opioid drugs are a class of pain-relieving medications that act on the nervous system to relieve pain by binding to opioid receptors.

Example: Morphine is a commonly used opioid drug to manage severe pain in patients. Quick Tip: Remember: Opioids are pain-relieving drugs that act on the nervous system; an example is morphine.

Trophic levels represent the feeding position of organisms in an ecosystem. The main trophic levels are:


Producers (1st level): Green plants (autotrophs).
Primary consumers (2nd level): Herbivores.
Secondary consumers (3rd level): Carnivores.
Tertiary consumers (4th level): Top predators.


Diagram:

Quick Tip: Remember: Trophic levels show energy flow, starting with producers and moving to primary, secondary, and tertiary consumers.

Biotechnology plays a crucial role in modern agriculture by improving crop yield, enhancing resistance to pests and diseases, and promoting sustainable farming practices.

Importance of Biotechnology in Agriculture:

(A) Genetically Modified (GM) Crops:

(B) Crops like Bt cotton and golden rice are engineered for higher yield and pest resistance.
(C) GM crops reduce the need for chemical pesticides, leading to eco-friendly farming.

(D) Improved Crop Quality:

(E) Enhances nutritional content, such as increased vitamin A in golden rice.

(F) Pest and Disease Resistance:

(G) Crops are engineered to resist pests, viruses, and fungi, reducing crop losses.

(H) Drought and Stress Tolerance:

(I) Genetically modified crops can withstand drought and adverse environmental conditions.

(J) Tissue Culture Technology:

(K) Helps in the mass production of disease-free plants.



Conclusion:

Biotechnology in agriculture contributes to food security, environmental sustainability, and the economic growth of farmers. Quick Tip: Remember: Biotechnology improves agricultural productivity through GM crops, pest resistance, and stress tolerance.

Polymerase Chain Reaction (PCR) is a technique used to amplify a specific segment of DNA, making millions of copies from a small sample.

Steps of PCR:

(A) Denaturation: DNA is heated to around 94-98°C to break hydrogen bonds, separating it into single strands.
(B) Annealing: Primers bind to the complementary DNA sequence at around 50-65°C.
(C) Extension: DNA polymerase synthesizes a new DNA strand by adding nucleotides at around 72°C.


Diagram:

Applications of PCR:

Used in medical diagnostics to detect genetic disorders and infectious diseases.
Essential in forensic science for DNA fingerprinting.
Applied in genetic research and cloning. Quick Tip: Remember: PCR involves denaturation, annealing, and extension; it is used for amplifying DNA in medical and forensic applications.

A biogas plant is a system that converts organic waste such as animal dung, plant material, and kitchen waste into biogas through anaerobic digestion. The biogas produced is primarily composed of methane (\ch{CH4) and carbon dioxide (\ch{CO2), which can be used for cooking and electricity generation.

Components of a Biogas Plant:

(A) Inlet Tank: Organic waste is mixed with water and fed into the digester.
(B) Digester: A sealed chamber where anaerobic bacteria break down the waste to produce biogas.
(C) Gas Holder: Collects the biogas generated during decomposition.
(D) Outlet Tank: The remaining slurry is removed and used as manure.


Diagram:

Advantages of Biogas:

Provides a renewable and eco-friendly energy source.
Reduces dependence on fossil fuels.
Produces nutrient-rich organic fertilizer. Quick Tip: Remember: A biogas plant converts organic waste into methane-rich gas through anaerobic digestion for cooking and energy.

Cancer is a group of diseases characterized by uncontrolled cell growth and division, leading to the formation of tumors that can invade surrounding tissues and spread to other parts of the body.

Causes of Cancer:

Genetic Factors: Inherited mutations in specific genes.
Carcinogens: Exposure to tobacco smoke, radiation, and harmful chemicals.
Viral Infections: Certain viruses such as HPV and Hepatitis B can trigger cancer.
Lifestyle Factors: Poor diet, lack of physical activity, and excessive alcohol consumption.


Treatment of Cancer:

(A) Surgery: Physical removal of the tumor.
(B) Radiation Therapy: Using high-energy rays to destroy cancer cells.
(C) Chemotherapy: Use of drugs to kill or slow the growth of cancer cells.
(D) Immunotherapy: Boosting the body's immune system to fight cancer. Quick Tip: Remember: Cancer is caused by genetic and environmental factors; treatments include surgery, radiation, chemotherapy, and immunotherapy.

Human evolution refers to the gradual development of modern humans from primate ancestors over millions of years. It involves changes in physical, behavioral, and genetic traits that have occurred over time.

Stages of Human Evolution:

(A) Australopithecus:

(B) Lived around 4-2 million years ago in Africa.
(C) Walked upright but had a small brain.

(D) Homo habilis:

(E) Known as "handy man" for using tools.
(F) Lived around 2 million years ago.

(G) Homo erectus:

(H) First species to use fire and migrate out of Africa.
(I) Lived around 1.5 million years ago.

(J) Homo neanderthalensis:

(K) Lived in Europe and Asia; adapted to cold climates.
(L) Used advanced tools and burial practices.

(M) Homo sapiens:

(N) Modern humans with advanced cognitive abilities.
(O) Evolved around 200,000 years ago in Africa.



Conclusion:

Human evolution is an ongoing process influenced by environmental adaptations, genetic mutations, and cultural advancements. Quick Tip: Remember: Human evolution involves Australopithecus to Homo sapiens, with key milestones in brain development and tool use.

Linkage and recombination are important concepts in genetics that explain the inheritance of genes located on chromosomes.

Linkage:

Linkage is the tendency of genes located close together on the same chromosome to be inherited together.
It was first observed by Thomas Morgan in fruit flies (Drosophila).
Example: Genes for body color and wing shape in fruit flies show linkage.


Recombination:

Recombination is the exchange of genetic material between homologous chromosomes during meiosis, leading to new genetic combinations.
It increases genetic diversity and occurs due to crossing over in meiosis.
Example: Crossing over between maternal and paternal chromosomes results in new traits in offspring.


Diagram:

Conclusion:

While linkage tends to keep genes together, recombination creates genetic variation, which is crucial for evolution and adaptation. Quick Tip: Remember: Linkage keeps genes inherited together; recombination introduces new gene combinations through crossing over.