Which of the following diagrams is correct with regard to the proximal (P) and distal (D) tubule ofthe Nephron.

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Answer

Nephron Tubule Diagram Explanation

🧠 Nephron Tubule Diagram Explanation

🔍 Understanding the Functions

The nephron consists of various tubules that help in reabsorption and secretion of substances. Two important segments are:

  • Proximal Tubule (P): Major site of reabsorption and some secretion.
  • Distal Tubule (D): Fine-tunes ion levels and regulates acid-base balance.

🔬 Key Functions

Segment Reabsorbed Secreted
Proximal Tubule (P) NaCl, HCO₃⁻, H₂O H⁺, NH₃
Distal Tubule (D) NaCl, H₂O, HCO₃⁻ H⁺, K⁺

📝 Option Analysis

Option Proximal Tubule (P) Distal Tubule (D) Verdict
(1) HCO₃⁻, NaCl, H₂O reabsorbed; H⁺ secreted NaCl, H₂O, HCO₃⁻ reabsorbed; K⁺, H⁺ secreted ✅ Correct
(2) HCO₃⁻, NaCl, H₂O reabsorbed; NH₃ secreted NaCl, H₂O, HCO₃⁻ reabsorbed; K⁺, H⁺ secreted 🔸 Partially Correct
(3) HCO₃⁻, NaCl, H₂O reabsorbed; H⁺, NH₃ secreted H₂O, HCO₃⁻ reabsorbed; NaCl, H⁺ wrongly placed ❌ Incorrect
(4) NaCl, HCO₃⁻ reabsorbed; H₂O incorrectly secreted NH₃ reabsorbed (wrong); H₂O secreted (wrong) ❌ Incorrect

✅ Final Answer

Correct Answer: (1) – Matches known physiological processes of the nephron.

📌 Takeaways

  • NaCl and HCO₃⁻ are reabsorbed in both P and D segments.
  • Water (H₂O) is reabsorbed in both tubules (not secreted).
  • H⁺ is secreted in both P and D for pH balance.
  • NH₃ is secreted in P; K⁺ is secreted in D.

In the seeds of cereals, the outer covering of endosperm separates the embryo by a protein-richlayer called

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Answer

Seed Structure in Cereals – Maize

Seed Structure in Cereals (e.g., Maize)

In cereal grains such as maize, the seed has a specialized structure adapted to store nutrients and protect the embryo. These features play a critical role in the seed’s development and successful germination.

Key Components of a Cereal Seed:

  • Seed Coat and Fruit Wall: In maize, the seed coat is thin and membranous, usually fused with the fruit wall, forming a protective covering around the seed.
  • Endosperm: This bulky tissue acts as a food storage area, supplying nutrients (mainly starch) to the growing embryo during germination.
  • Aleurone Layer: A protein-rich layer that surrounds the endosperm. It helps regulate enzyme activity and supports the breakdown of stored food into usable energy for the embryo.

Biological Importance:

These components work together to ensure the seed is protected and well-prepared for germination. The fused seed coat and fruit wall provide durability and reduce water loss, while the aleurone layer and endosperm support early seedling growth through nutrient supply and enzymatic activity.

Find the correct statements:A. In human pregnancy, the major organ systemsare formed at the end of 12 weeks.B. In human pregnancy the major organ systemsare formed at the end of 8 weeks.C. In human pregnancy heart is formed after onemonth of gestation.D. In human pregnancy, limbs and digits developby the end of second month.E. In human pregnancy the appearance of hairusually observed in the fifth month.Choose the correct answer from the options givenbelow:

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Answer

Fetal Development – First Trimester

Fetal Development: End of the First Trimester

By the end of 12 weeks of pregnancy (the end of the first trimester), most of the major organ systems are formed. This marks a crucial milestone in fetal development.

Key Highlights of Development by 12 Weeks:

  • Organogenesis: Most major organs are structurally present, though not fully functional.
  • Central Nervous System: The brain and spinal cord continue to develop and grow in complexity.
  • Circulatory System: The heart is beating and actively pumping blood throughout the body.
  • Digestive & Excretory Systems: Intestines begin settling into place; kidneys start producing urine.
  • Limb Development: Arms, legs, fingers, and toes are formed; slight fetal movement may begin.
  • Facial Features: Eyes, ears, and nose take shape; external genitalia begin to differentiate.

Importance of the First Trimester:

The first trimester is a critical period for development. All major organ systems are established, making the fetus particularly vulnerable to environmental influences such as drugs, infections, and radiation.

Match List-I with List-II.List-I List-IIA. Chlorophyll a I. Yellow-green B. Chlorophyll b II. Yellow C. Xanthophylls III. Blue-green D. Carotenoids IV. Yellow toYellow-orangeChoose the option with all correct matches.

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Answer

Leaf Pigments and Photosynthesis

Chromatographic Separation of Leaf Pigments

Chromatographic techniques reveal that the green color seen in leaves is not the result of a single pigment. Instead, it is due to the presence of four different pigments, each contributing uniquely to the leaf’s appearance and photosynthesis process.

Major Pigments in Leaves:

  • Chlorophyll a – Bright or blue-green in color (in chromatograms). It is the primary pigment responsible for capturing light energy in photosynthesis.
  • Chlorophyll b – Yellow-green pigment. It acts as an accessory pigment, expanding the range of light absorption.
  • Xanthophylls – Yellow pigments that assist in light absorption and help in dissipating excess light energy.
  • Carotenoids – Yellow to yellow-orange pigments that support light capture and protect chlorophyll from light-induced damage.

Role in Photosynthesis:

These pigments are vital in capturing light energy used in photosynthesis. Each pigment absorbs specific wavelengths of light, giving it a characteristic color. By working together, these pigments ensure efficient light absorption and energy conversion, while also protecting the plant from damage due to excessive light exposure.

Match List-I with List-II.List-I List-IIA. Centromere I. Mitochondrion B. Cilium II. Cell division C. Cristae III. Cell movement D. Cell membrane IV. Phospholipid Bilayer Choose the correct answer from the options given below:

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Answer

Cell Structures and Functions

Cell Structures and Their Functions

This table illustrates the relationship between specific cellular structures and their respective functions:

Label Structure Function
A Centromere Cell division (site where spindle fibres attach during mitosis)
B Cilium Cell movement (helps in locomotion or movement of substances)
C Cristae Mitochondrion (infoldings of the inner mitochondrial membrane)
D Cell membrane Phospholipid bilayer (basic structure of the plasma membrane)

Detailed Explanations

Centromere: Crucial for chromosome movement during cell division by serving as an attachment site for spindle fibres.

Cilium: Hair-like projections on cell surfaces that facilitate motion or transport of substances over the cell surface.

Cristae: The folded inner membrane of mitochondria, increasing surface area for ATP-producing enzymes during cellular respiration.

Cell membrane: A semi-permeable membrane composed of a phospholipid bilayer, controlling the transport of materials in and out of the cell.

Which are correct A. Computed tomography and magneticresonance imaging detect cancers of internalorgans.B. Chemotherapeutics drugs are used to kill noncancerous cells C. interferon activate the cancer patients’immune system and helps in destroying thetumour. D. Chemotherapeutic drugs are biologicalresponse modifiers.E. In the case of leukaemia blood cells counts aredecreased.Choose the correct answer from the option givenbelow:

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Answer

Cancer Detection and Treatment

Cancer Detection and Treatment

1. Diagnosis of Cancer

Cancers of internal organs can be detected using advanced imaging techniques:

  • Computed Tomography (CT): Combines X-rays and computer technology to create detailed cross-sectional images of the body.
  • Magnetic Resonance Imaging (MRI): Uses strong magnetic fields and radio waves to produce detailed images of internal organs and tissues.

2. Chemotherapy

Chemotherapeutic drugs are used to kill or inhibit the growth of cancerous cells. These drugs are especially effective against rapidly dividing cells, making them a key component in cancer treatment.

3. Immunotherapy

Patients are often given substances known as biological response modifiers, which enhance the body’s immune system. One such substance is α-interferon, a protein that activates the immune system to recognize and destroy tumor cells.

4. Leukemia

Leukemia is a type of cancer that affects the blood and bone marrow. It is characterized by a significant increase in the number of abnormal white blood cells.

This comprehensive approach—combining early detection, chemotherapy, and immunotherapy—helps improve cancer treatment outcomes.

The correct sequence of events in the life cycle of bryophytes is A. Fusion of antherozoid with egg.B. Attachment of gametophyte to substratum.C. Reduction division to produce haploid spores.D. Formation of sporophyte.E. Release of antherozoids into water.Choose the correct answer from the option givenbelow:

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Answer

Life Cycle of Bryophytes

Life Cycle of Bryophytes: Sequence of Events

Bryophytes, such as mosses and liverworts, exhibit a clear alternation of generations, with the haploid gametophyte being the dominant phase. The following steps outline the correct sequence of events in the bryophyte life cycle:

Sequence of Events:

  • B: Attachment of gametophyte to substratum – The gametophyte anchors to the surface using rhizoids for stability and nutrient absorption.
  • E: Release of antherozoids into water – Male gametes (antherozoids) are released from antheridia into a film of water, a prerequisite for fertilization.
  • A: Fusion of antherozoid with egg – Antherozoids swim to archegonia, where fertilization occurs, forming a diploid zygote.
  • D: Formation of sporophyte – The zygote develops into a sporophyte, which remains attached to the gametophyte and is composed of a foot, seta, and capsule.
  • C: Reduction division to produce haploid spores – Meiosis occurs in the capsule, producing haploid spores that can grow into new gametophytes.

Alternation of Generations

This sequence demonstrates the alternation of generations in bryophytes: the dominant gametophyte generation gives rise to a dependent sporophyte after fertilization. The sporophyte produces spores that regenerate the gametophyte, ensuring continuation of the life cycle and genetic diversity.

Find the statement that is NOT correct with regardto the structure of monocot stem.

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Answer

Monocot Stem Anatomy

Anatomy of a Monocot Stem

The monocot stem shows unique structural characteristics, which distinguish it from the dicot stem. These features help monocot plants in support and transport.

Key Features of a Monocot Stem:

  • Sclerenchymatous Hypodermis: The hypodermis is made of lignified sclerenchyma cells, providing mechanical strength. Unlike dicots, it is not parenchymatous.
  • Scattered Vascular Bundles: Vascular bundles are scattered throughout the ground tissue, not arranged in a ring.
  • Conjoint and Closed Vascular Bundles: Xylem and phloem are present in the same bundle (conjoint), and no cambium is present between them (closed), hence no secondary growth.
  • Absence of Phloem Parenchyma: Monocot phloem lacks phloem parenchyma; it contains sieve tubes and companion cells only.

Summary Table: Monocot Stem Anatomy

Feature Monocot Stem
Hypodermis Sclerenchymatous
Vascular Bundle Arrangement Scattered
Vascular Bundle Type Conjoint and Closed
Phloem Parenchyma Absent
Secondary Growth Absent

Multiply or divide the following measurements. Be sure each answer you enter contains the correct number of significant

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Answer

Significant Figures in Multiplication and Division

🧪 Significant Figures in Multiplication and Division

🎯 Core Concept

When multiplying or dividing measured values:

📌 The final answer must have the same number of significant figures as the measurement with the fewest significant figures.

🔍 Example 1: 340 g ÷ 63.761 mL

340 g → 2 sig figs
63.761 mL → 5 sig figs

340 ÷ 63.761 = 5.332…
✔️ Final Answer: 5.3 g/mL (2 sig figs)

🔍 Example 2: 355.6 g ÷ 0.65 mL

355.6 g → 4 sig figs
0.65 mL → 2 sig figs

355.6 ÷ 0.65 = 547.0769…
✔️ Final Answer: 550 g/mL (2 sig figs)

🔍 Example 3: 7.8084 mol/L × 3.825 L

7.8084 → 5 sig figs
3.825 → 4 sig figs

7.8084 × 3.825 = 29.86913
✔️ Final Answer: 29.86 mol (4 sig figs)

✅ Summary Rule Table

Operation Rule
Multiplication Use the fewest significant figures among the inputs
Division Use the fewest significant figures among the inputs
Rounding Round only at the end, not during intermediate steps

Name the class of enzyme that usually catalyze the following reaction:S – G + S# → S + S# – GWhere, G → a group other than hydrogenS → a substrateS

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Answer

Transferase Enzyme Reactions

Transferase Reactions and Mechanism

S–G + S# → S + S#–G

Where:

  • G is a functional group other than hydrogen.
  • S and S# are substrate molecules.

Explanation of the Reaction:

This reaction represents the transfer of a functional group (G) from one substrate (S) to another substrate (S#).

  • S–G is the donor molecule that originally carries the group G.
  • S# is the acceptor molecule that will receive the group G.
  • After the transfer, S becomes free of G, and S#–G becomes the modified molecule with the newly added group.

Role of Transferases:

Transferases are a class of enzymes that catalyze the transfer of specific functional groups from one molecule to another. They are involved in many crucial biochemical processes.

  • Aminotransferases: Transfer amino groups.
  • Methyltransferases: Transfer methyl groups.
  • Kinases: Transfer phosphate groups (a subclass of phosphotransferases).

Significance in Biochemistry:

  • Transferase reactions play a vital role in metabolic pathways and cellular regulation.
  • They are involved in processes like signal transduction, energy transfer, and biosynthesis.
  • Understanding these enzymes is essential in biotechnology, medicine, and pharmacology.