10th Science Mid Term Exam Solutions - 2024
ARIYALUR DISTRICT | SECOND MID TERM EXAMINATION - 2024 | Std: 10 SCIENCE
Part I: Choose the correct answer (8 x 1 = 8)
1) If a sound wave travels with a frequency of 1.25 x 10⁴ Hz at 344 ms⁻¹, the wavelength will be
Answer: c) 0.02752 m
Explanation:
Given: Frequency (f) = \(1.25 \times 10^4\) Hz, Speed (v) = 344 m/s.
The formula for wavelength (\(\lambda\)) is \(\lambda = \frac{v}{f}\).
\(\lambda = \frac{344}{1.25 \times 10^4} = \frac{344}{12500} = 0.02752\) m.
Explanation:
Given: Frequency (f) = \(1.25 \times 10^4\) Hz, Speed (v) = 344 m/s.
The formula for wavelength (\(\lambda\)) is \(\lambda = \frac{v}{f}\).
\(\lambda = \frac{344}{1.25 \times 10^4} = \frac{344}{12500} = 0.02752\) m.
2) The energy released in a nuclear fission process is about...
Answer: c) 200 MeV
Explanation: On average, the fission of one uranium-235 nucleus releases approximately 200 million electron volts (MeV) of energy.
Explanation: On average, the fission of one uranium-235 nucleus releases approximately 200 million electron volts (MeV) of energy.
3) Which of the following is not an "element + element → Compound" type reaction?
Answer: c) \(2CO_{(g)} + O_{2(g)} \rightarrow 2CO_{2(g)}\)
Explanation: In this reaction, a reactant Carbon Monoxide (CO) is a compound, not an element. The other options show reactions between two elements to form a compound.
Explanation: In this reaction, a reactant Carbon Monoxide (CO) is a compound, not an element. The other options show reactions between two elements to form a compound.
4) Rectified spirit is an aqueous solution which contains about .......... of ethanol
Answer: 95.5% (Based on standard value)
Explanation: Rectified spirit is a highly concentrated ethanol containing about 95.5% ethanol and 4.5% water. While not an exact option, 93.5% is the closest choice provided in the paper.
Explanation: Rectified spirit is a highly concentrated ethanol containing about 95.5% ethanol and 4.5% water. While not an exact option, 93.5% is the closest choice provided in the paper.
5) The 'use and disuse theory' was proposed by ..........
Answer: c) Jean Baptiste Lamarck
Explanation: The theory of inheritance of acquired characteristics, also known as the use and disuse theory, was proposed by Jean Baptiste Lamarck.
Explanation: The theory of inheritance of acquired characteristics, also known as the use and disuse theory, was proposed by Jean Baptiste Lamarck.
6) We can cut the DNA with the help of
Answer: b) restriction endonucleases
Explanation: Restriction endonucleases, also known as restriction enzymes, are used to cut DNA at specific recognition sites. They are often called 'molecular scissors'.
Explanation: Restriction endonucleases, also known as restriction enzymes, are used to cut DNA at specific recognition sites. They are often called 'molecular scissors'.
7) In a hexaploid wheat (2n=6x = 42) the haploid (n) and the basic (x) number of chromosomes respectively are
Answer: d) n = 21 and x = 7
Explanation:
Given: Diploid number (2n) = 42. So, the haploid number (n) = 42 / 2 = 21.
Given: 6x = 42. So, the basic chromosome number (x) = 42 / 6 = 7.
Explanation:
Given: Diploid number (2n) = 42. So, the haploid number (n) = 42 / 2 = 21.
Given: 6x = 42. So, the basic chromosome number (x) = 42 / 6 = 7.
8) Cancer of the epithelial cells is called
Answer: c) Carcinoma
Explanation: Carcinoma is a type of cancer that originates in the epithelial cells, which are the cells that line the surfaces of the body.
Explanation: Carcinoma is a type of cancer that originates in the epithelial cells, which are the cells that line the surfaces of the body.
Part II: Answer any six questions. Q.No.15 compulsory (6 x 2 = 12)
9) Match the following
| Column A | Column B |
|---|---|
| a) Soddy Fajan | Displacement law |
| b) Irene Curie | Artificial Radioactivity |
| c) Henry Bequerel | Natural radioactivity |
| d) Albert Einstein | Mass energy equivalence |
10) Differentiate reversible and irreversible reactions.
| Reversible Reactions | Irreversible Reactions |
|---|---|
| A reaction that can proceed in both forward and backward directions. | A reaction that can proceed only in the forward direction. |
| Reactants can be regenerated from the products. | Reactants cannot be regenerated from the products. |
| It attains equilibrium. | It does not attain equilibrium. |
| Example: \(PCl_5 \rightleftharpoons PCl_3 + Cl_2\) | Example: \(C + O_2 \rightarrow CO_2\) |
11) Name the simplest ketone and give its structural formula
Name: The simplest ketone is Propanone, commonly known as Acetone.
Molecular Formula: $CH_3COCH_3$
Structural Formula:
H O H
| || |
H-C--C--C-H
| |
H H
12) Define Ethnobotany and write its importance.
Ethnobotany: Ethnobotany is the scientific study of the relationship that exists between people and plants. It explores how local cultures and peoples use native plants for food, medicine, shelter, and cultural purposes.
Importance:
Importance:
- It provides traditional knowledge about the use of plants for medicinal and other purposes.
- It helps in the discovery of new sources of drugs, food, and other useful plant products.
- It plays a vital role in the conservation of plant biodiversity and cultural heritage.
13) State the applications of DNA fingerprinting technique.
Applications of DNA fingerprinting:
- Forensic Science: Used to identify criminals from biological samples (like blood, hair, semen) left at crime scenes.
- Paternity and Maternity Testing: Used to resolve disputes of parentage by comparing the DNA of the child with the potential parents.
- Medical Diagnostics: Helps in identifying and diagnosing inherited genetic disorders.
- Conservation of Wildlife: Used to track endangered species and prevent illegal poaching by identifying the source of animal products.
14) What are the various routes by which transmission of human deficiency virus (HIV) takes place?
Routes of HIV transmission:
- Unprotected Sexual Contact: Transmission through semen, vaginal fluids, and rectal fluids during sexual intercourse.
- Sharing Needles: Sharing contaminated needles, syringes, or other drug injection equipment.
- Blood Transfusion: Receiving blood or blood products contaminated with HIV.
- Mother to Child (Perinatal Transmission): An infected mother can pass the virus to her baby during pregnancy, childbirth, or breastfeeding.
15) (Compulsory) A strong sound signal is sent from a ship towards the bottom of the sea. It is received back after 1s. What is the depth of sea given that the speed of sound in water 1450 m s⁻¹?
Given:
Total time taken for the sound to travel to the bottom and back (t) = 1 s.
Speed of sound in water (v) = 1450 m/s.
To find: Depth of the sea (d).
Formula: The distance travelled by the sound is twice the depth of the sea (2d).
So, \(2d = v \times t\).
Calculation:
\(d = \frac{v \times t}{2}\)
\(d = \frac{1450 \times 1}{2}\)
\(d = \frac{1450}{2}\)
\(d = 725\) m.
Therefore, the depth of the sea is 725 meters.
Total time taken for the sound to travel to the bottom and back (t) = 1 s.
Speed of sound in water (v) = 1450 m/s.
To find: Depth of the sea (d).
Formula: The distance travelled by the sound is twice the depth of the sea (2d).
So, \(2d = v \times t\).
Calculation:
\(d = \frac{v \times t}{2}\)
\(d = \frac{1450 \times 1}{2}\)
\(d = \frac{1450}{2}\)
\(d = 725\) m.
Therefore, the depth of the sea is 725 meters.
Part III: Answer any four questions (4 x 4 = 16)
16) a) Mention two cases in which there is no Doppler effect in sound?
b) Explain why the ceilings of concert halls are curved.
a) Cases with no Doppler effect:
The ceilings of concert halls, auditoriums, and theatres are curved to ensure that sound is reflected and distributed evenly across the entire hall. This design helps in:
- When both the source of sound and the listener are at rest.
- When the source and the listener move in such a way that the distance between them remains constant (e.g., moving in parallel paths with the same velocity).
The ceilings of concert halls, auditoriums, and theatres are curved to ensure that sound is reflected and distributed evenly across the entire hall. This design helps in:
- Uniform Sound Distribution: A curved (concave) surface reflects sound waves to spread them out over a wide area, so that people in all parts of the hall can hear the sound clearly.
- Prevention of Echoes: It prevents the formation of standing waves and echoes that can be caused by sound reflecting off large, flat surfaces. This improves the overall acoustic quality of the space.
17) Write the features of natural and artificial radioactivity.
| Feature | Natural Radioactivity | Artificial Radioactivity |
|---|---|---|
| Origin | It is a spontaneous process occurring in naturally found unstable elements. | It is an induced process, caused by bombarding stable nuclei with particles. |
| Control | The rate of decay cannot be controlled. | The rate of decay can be controlled. |
| Elements | Generally occurs in elements with atomic number greater than 82. | Can be induced in many lighter, stable elements. |
| Example | The decay of Uranium-238. | The conversion of Aluminium to radioactive Phosphorus by alpha particle bombardment. |
18) Differentiate soaps and detergents.
| Feature | Soaps | Detergents |
|---|---|---|
| Chemical Nature | Sodium or potassium salts of long-chain fatty acids. | Sodium salts of long-chain benzene sulphonic acids or alkyl hydrogen sulphates. |
| Action in Hard Water | Ineffective. Forms an insoluble precipitate (scum) with calcium and magnesium ions. | Effective. Does not form scum and works well in hard water. |
| Biodegradability | Generally biodegradable as they are derived from natural fats and oils. | Many are non-biodegradable, which can cause water pollution. |
| Cleansing Action | Have a weaker cleansing action compared to detergents. | Have a stronger cleansing action. |
19) How do you differentiate homologous organs from analogous organs?
| Feature | Homologous Organs | Analogous Organs |
|---|---|---|
| Origin & Structure | Have a common origin and similar basic structure. | Have different origins and different basic structures. |
| Function | Perform different functions. | Perform similar functions. |
| Evolution | Indicate divergent evolution (common ancestor, adapted to different environments). | Indicate convergent evolution (different ancestors, adapted to a similar environment). |
| Example | Forelimbs of a man, whale, and bat. | Wings of a bird and an insect. |
20) Discuss the importance of biotechnology in the field of medicine.
Biotechnology has revolutionized the field of medicine in numerous ways:
- Pharmaceuticals Production: It enables the mass production of vital medicines like human insulin for diabetics, human growth hormone, and blood clotting factors for hemophiliacs using genetically engineered bacteria.
- Vaccines: Development of safer and more effective recombinant vaccines (e.g., Hepatitis B vaccine) and edible vaccines.
- Gene Therapy: It offers the potential to correct genetic disorders by replacing a faulty gene with a healthy one. This is used in treating diseases like cystic fibrosis and severe combined immunodeficiency (SCID).
- Diagnosis: Techniques like Polymerase Chain Reaction (PCR) and ELISA are used for the early and accurate diagnosis of diseases like HIV/AIDS and genetic disorders.
- Stem Cell Technology: Stem cells have the potential to differentiate into various cell types and are used in regenerative medicine to repair or replace damaged tissues and organs.
21) Suggest measures to overcome the problems of an alcoholic.
Overcoming alcoholism requires a comprehensive approach involving medical, psychological, and social support:
- Medical Assistance: Seeking help from a doctor for detoxification, which is the process of safely withdrawing from alcohol under medical supervision. Medications may be prescribed to manage withdrawal symptoms.
- Psychological Counselling and Therapy: Individual or group therapy can help an alcoholic understand the root causes of their drinking, develop coping mechanisms, and learn strategies to avoid relapse.
- Support Groups: Joining support groups like Alcoholics Anonymous (AA) provides a community of peers who share their experiences and support each other in maintaining sobriety.
- Family and Social Support: Strong support from family and friends is crucial. Educating the family about alcoholism helps them provide constructive support.
- Rehabilitation Programs: Enrolling in an inpatient or outpatient rehabilitation program offers a structured environment for recovery.
22) What would be the p" of an aqueous solution of sulphuric acid which is 5 x 10⁻⁵ mol litre⁻¹ in concentration?
Given:
Concentration of Sulphuric acid, \([H_2SO_4] = 5 \times 10^{-5}\) M.
Dissociation:
Sulphuric acid is a strong acid and dissociates completely in water to give two hydrogen ions (\(H^+\)) per molecule.
$$ H_2SO_4 \rightarrow 2H^+ + SO_4^{2-} $$ Calculation of \(H^+\) concentration:
The concentration of hydrogen ions will be twice the concentration of the acid.
\([H^+] = 2 \times [H_2SO_4]\)
\([H^+] = 2 \times (5 \times 10^{-5})\) M
\([H^+] = 10 \times 10^{-5}\) M = \(1 \times 10^{-4}\) M.
Calculation of pH:
The formula for pH is \(pH = -\log_{10}[H^+]\).
\(pH = -\log_{10}(1 \times 10^{-4})\)
\(pH = -(\log_{10}(1) + \log_{10}(10^{-4}))\)
\(pH = -(0 - 4)\)
\(pH = 4\)
The pH of the solution is 4.
Concentration of Sulphuric acid, \([H_2SO_4] = 5 \times 10^{-5}\) M.
Dissociation:
Sulphuric acid is a strong acid and dissociates completely in water to give two hydrogen ions (\(H^+\)) per molecule.
$$ H_2SO_4 \rightarrow 2H^+ + SO_4^{2-} $$ Calculation of \(H^+\) concentration:
The concentration of hydrogen ions will be twice the concentration of the acid.
\([H^+] = 2 \times [H_2SO_4]\)
\([H^+] = 2 \times (5 \times 10^{-5})\) M
\([H^+] = 10 \times 10^{-5}\) M = \(1 \times 10^{-4}\) M.
Calculation of pH:
The formula for pH is \(pH = -\log_{10}[H^+]\).
\(pH = -\log_{10}(1 \times 10^{-4})\)
\(pH = -(\log_{10}(1) + \log_{10}(10^{-4}))\)
\(pH = -(0 - 4)\)
\(pH = 4\)
The pH of the solution is 4.
Part IV: Answer all the questions (2 x 7 = 14)
23) a) i) What is an echo? What are the medical applications of echo?
ii) Compare the properties of alpha, beta and gamma radiations.
i) Echo and its Medical Applications
An echo is the phenomenon of repetition of sound caused by the reflection of sound waves from a surface. For an echo to be heard distinctly, the time interval between the original sound and the reflected sound must be at least 0.1 seconds, and the reflecting surface must be at least 17.2 meters away in air.
Medical Applications: The principle of echo is used in ultrasonography.
An echo is the phenomenon of repetition of sound caused by the reflection of sound waves from a surface. For an echo to be heard distinctly, the time interval between the original sound and the reflected sound must be at least 0.1 seconds, and the reflecting surface must be at least 17.2 meters away in air.
Medical Applications: The principle of echo is used in ultrasonography.
- Echocardiography: Ultrasonic waves are used to create images of the heart, its valves, and blood flow.
- Ultrasonography: Used to monitor fetal development during pregnancy, and to image internal organs like the liver, kidneys, and gall bladder for diagnostic purposes.
| Property | Alpha (\(\alpha\)) Ray | Beta (\(\beta\)) Ray | Gamma (\(\gamma\)) Ray |
|---|---|---|---|
| Nature | Helium nucleus (\(^{4}_{2}He\)) | Electron (\(^{-1}_{0}e\)) | Electromagnetic wave |
| Charge | Positive charge (+2e) | Negative charge (-1e) | No charge (neutral) |
| Ionising Power | Very high (100 times \(\beta\), 10,000 times \(\gamma\)) | Moderate (less than \(\alpha\)) | Very low |
| Penetrating Power | Very low (stopped by a sheet of paper) | Moderate (stopped by a thin aluminium foil) | Very high (stopped by a thick block of lead) |
| Effect of Electric/Magnetic Field | Deflected towards the negative plate/pole. | Deflected towards the positive plate/pole. | Not deflected. |
23) b) (OR)
i) Why ordinary soap is not suitable for using with hard water?
ii) The molecular formula of an alcohol is C₄H₁₀O. The locant number of its -OH group is 2.
1. Draw its structural formula
2. Give its IUPAC name
3. Is it saturated or unsaturated?
i) Soap with Hard Water
Ordinary soap is not suitable for use with hard water because hard water contains dissolved salts of calcium (\(Ca^{2+}\)) and magnesium (\(Mg^{2+}\)) ions. When soap (which is a sodium or potassium salt of a fatty acid, e.g., sodium stearate) is used in hard water, it reacts with these ions to form an insoluble, sticky precipitate called scum. This scum does not lather, reduces the cleansing efficiency of the soap, and leaves a residue on clothes and skin. $$ 2C_{17}H_{35}COONa_{(aq)} + CaCl_{2(aq)} \rightarrow (C_{17}H_{35}COO)_2Ca_{(s)} \downarrow + 2NaCl_{(aq)} $$(Soap) + (Hard Water) \(\rightarrow\) (Scum) + (Salt)
ii) Alcohol with formula C₄H₁₀O
Given that the -OH group is at position 2.
1. Structural Formula: $$ CH_3 - CH(OH) - CH_2 - CH_3 $$
2. IUPAC Name: The main chain has 4 carbon atoms (but-). The functional group is an alcohol (-ol) located at the 2nd carbon. So, the name is Butan-2-ol.
3. Saturated or Unsaturated? It is a saturated compound. This is because all the bonds between the carbon atoms in the chain are single bonds. There are no double or triple bonds between carbon atoms.
Ordinary soap is not suitable for use with hard water because hard water contains dissolved salts of calcium (\(Ca^{2+}\)) and magnesium (\(Mg^{2+}\)) ions. When soap (which is a sodium or potassium salt of a fatty acid, e.g., sodium stearate) is used in hard water, it reacts with these ions to form an insoluble, sticky precipitate called scum. This scum does not lather, reduces the cleansing efficiency of the soap, and leaves a residue on clothes and skin. $$ 2C_{17}H_{35}COONa_{(aq)} + CaCl_{2(aq)} \rightarrow (C_{17}H_{35}COO)_2Ca_{(s)} \downarrow + 2NaCl_{(aq)} $$
ii) Alcohol with formula C₄H₁₀O
Given that the -OH group is at position 2.
1. Structural Formula: $$ CH_3 - CH(OH) - CH_2 - CH_3 $$
2. IUPAC Name: The main chain has 4 carbon atoms (but-). The functional group is an alcohol (-ol) located at the 2nd carbon. So, the name is Butan-2-ol.3. Saturated or Unsaturated? It is a saturated compound. This is because all the bonds between the carbon atoms in the chain are single bonds. There are no double or triple bonds between carbon atoms.
24) a) i) Name the types of stem cells.
ii) With a neat labeled diagram explain the techniques involved in gene cloning.
i) Types of Stem Cells
Stem cells are broadly classified into two main types based on their origin:
Gene cloning is the process of making multiple, identical copies of a particular piece of DNA. The most common method uses bacteria and plasmids.
Stem cells are broadly classified into two main types based on their origin:
- Embryonic Stem Cells (ESCs): These are derived from the inner cell mass of a blastocyst (an early-stage embryo). They are pluripotent, meaning they can differentiate into any of the over 200 cell types of the adult body.
- Adult Stem Cells (Somatic Stem Cells): These are found in various tissues of the body after development (e.g., bone marrow, skin, brain). They are multipotent, meaning they can differentiate into a limited range of cell types, typically related to the tissue they are from. Examples include hematopoietic stem cells (form blood cells) and mesenchymal stem cells (form bone, cartilage, and fat cells).
Gene cloning is the process of making multiple, identical copies of a particular piece of DNA. The most common method uses bacteria and plasmids.
Steps in Gene Cloning:
- Isolation of DNA: The gene of interest (e.g., the human insulin gene) is isolated from human DNA. A plasmid (a small, circular piece of DNA) is isolated from a bacterium (like E. coli).
- Cutting with Restriction Enzyme: Both the human DNA and the plasmid DNA are cut with the same restriction enzyme. This enzyme cuts the DNA at a specific sequence, creating "sticky ends" which are complementary to each other.
- Ligation: The cut human gene and the cut plasmid are mixed together. The sticky ends of the gene pair up with the sticky ends of the plasmid. An enzyme called DNA ligase is added to permanently join them, forming a recombinant plasmid (or recombinant DNA).
- Transformation: The recombinant plasmids are introduced into host bacteria. This process is called transformation. Not all bacteria will take up the plasmid.
- Screening and Selection: The bacteria are grown on a culture medium that allows only the bacteria containing the recombinant plasmid to survive (e.g., using antibiotic resistance genes on the plasmid).
- Cloning: The transformed bacteria are cultured. As the bacteria reproduce rapidly, they make millions of copies of the recombinant plasmid, and thus, millions of copies of the gene of interest.
24) b) (OR)
i) What precautions can be taken for preventing heart diseases?
ii) What is metastasis?
i) Precautions for Preventing Heart Diseases
Several lifestyle modifications and preventive measures can significantly reduce the risk of heart diseases:
Metastasis is the process by which cancer cells spread from the place where they first formed (the primary tumor) to other parts of the body. Cancer cells can break away from the primary tumor, travel through the bloodstream or the lymph system, and form new, secondary tumors in other organs or tissues. The ability to metastasize is a hallmark of malignant (cancerous) tumors and is the primary cause of death from cancer.
Several lifestyle modifications and preventive measures can significantly reduce the risk of heart diseases:
- Healthy Diet: Consume a balanced diet rich in fruits, vegetables, whole grains, and lean proteins. Limit the intake of saturated fats, trans fats, cholesterol, sodium (salt), and added sugars.
- Regular Physical Activity: Engage in at least 150 minutes of moderate-intensity aerobic exercise (like brisk walking or cycling) per week.
- Maintain a Healthy Weight: Being overweight or obese increases the risk of heart disease. Weight management through diet and exercise is crucial.
- Avoid Tobacco: Smoking and the use of tobacco products are major risk factors. Quitting smoking is one of the best things you can do for your heart.
- Limit Alcohol Consumption: Excessive alcohol intake can raise blood pressure and contribute to heart failure.
- Manage Stress: Chronic stress can contribute to heart disease. Practice stress-management techniques like meditation, yoga, or hobbies.
- Regular Health Screenings: Regularly check blood pressure, cholesterol levels, and blood sugar levels to monitor and manage risk factors like hypertension, high cholesterol, and diabetes.
Metastasis is the process by which cancer cells spread from the place where they first formed (the primary tumor) to other parts of the body. Cancer cells can break away from the primary tumor, travel through the bloodstream or the lymph system, and form new, secondary tumors in other organs or tissues. The ability to metastasize is a hallmark of malignant (cancerous) tumors and is the primary cause of death from cancer.