Part A: Evolution
1. LAMARCKISM (Theory of Inheritance of Acquired Characters)
Q1. Who proposed the theory of inheritance of acquired characters and what is it called?
A1. Jean Baptiste Lamarck (1744-1829), a French biologist, proposed this theory which is known as Lamarckism.
Q2. Explain Lamarckism with the example of giraffe's neck evolution.
A2. According to Lamarckism:
- Giraffes originally had short necks and fed on ground vegetation
- Due to food scarcity, they stretched their necks to reach leaves on higher branches
- Through continuous use, their necks gradually elongated
- These acquired longer necks were passed to their offspring
- Over generations, giraffes with longer necks emerged
Q3. What are the main indicators of Lamarckism?
A3. The main indicators are:
- Change in environment
- Formation of acquired characters
- Inheritance of acquired characters
- Survival advantage in changed environment
Q4. What is the major criticism of Lamarck's theory?
A4. Later scientists proved that acquired characters do not cause changes in the genetic structure of organisms and therefore are not inherited to the next generation.
2. DARWINISM (Theory of Natural Selection)
Q5. Who proposed the theory of natural selection and when?
A5. Charles Robert Darwin (1809-1882), an English naturalist, proposed the theory of natural selection. He published his ideas in the book "On the Origin of Species" in 1859.
Q6. Describe Darwin's voyage and its significance.
A6. Darwin embarked on a five-year voyage (1831-1836) on the ship H.M.S. Beagle at age 22. He explored South America, Australia, and the Galapagos Islands, meticulously observing and documenting flora and fauna diversity. This voyage provided crucial evidence for his theory of evolution.
Q7. How did Thomas Malthus influence Darwin's theory?
A7. Thomas Malthus argued that human population grows faster than food production, leading to poverty, disease, and war. This perspective influenced Darwin's understanding of the struggle for existence and competition for limited resources.
Q8. Explain Darwin's observations of Galapagos finches.
A8. Darwin observed about 14 different species of finches on the Galapagos Islands:
- Ground finches: seed-eaters, ground dwellers
- Cactus finches: live on cacti, eat seeds
- Tree finches: live in trees, insectivorous
- Main difference: beak shape and size adapted to their food sources
- Birds with suitable beak shapes survived and reproduced more successfully
Q9. What are the five main principles of Darwin's theory of natural selection?
A9. The five principles are:
- Over-production: Organisms produce more offspring than the environment can support
- Variations: Organisms show differences in features like size, immunity, etc.
- Struggle for existence: Limited resources lead to competition
- Survival of the fittest: Organisms with favorable variations survive
- Natural selection: Favorable variations are passed to next generations, leading to evolution of new species
Q10. Compare Lamarckism and Darwinism using the giraffe example.
A10. Lamarckism: Environment causes variations → Giraffes stretch necks → Acquired longer necks → Transmitted to offspring
Darwinism: Giraffes had varying neck lengths → Environment selects longer necks → Only long-necked giraffes survived competition → New species evolved
3. NEO-DARWINISM
Q11. What are the limitations of Darwin's original theory?
A11. Darwin had no knowledge about:
- Genetic basis of variations
- Mechanism of inheritance
- Chromosomes and genes
Q12. What is Neo-Darwinism?
A12. Neo-Darwinism is the modern evolutionary theory that combines Darwin's natural selection with:
- Mendel's genetic discoveries
- Knowledge of chromosomes and genes
- Understanding that variations arise from genetic changes, genetic recombination, and gene flow
- Evidence from population genetics, paleontology, and environmental science
Q13. How is evolutionary theory applied in modern medicine?
A13. Applications include:
- Evolutionary clinical medicine studies how bacteria/viruses evolve drug resistance
- Development of new treatment methods
- Personalized medicine based on individual genes and family history
- Using DNA studies and AI to understand diseases
4. SPECIATION AND EVOLUTIONARY RELATIONSHIPS
Q14. What is speciation?
A14. Speciation is the process by which new species arise from a common ancestor. It's the process responsible for Earth's biodiversity.
Q15. Explain LUCA and MRCA.
A15.
- LUCA (Last Universal Common Ancestor): The common ancestor from which all species are thought to have descended
- MRCA (Most Recent Common Ancestor): The most recent common ancestor shared by different species
Q16. How do new species form?
A16. Process of species formation:
- Members of a population reproduce with variations
- Population gets isolated by ecological/genetic factors
- Variations accumulate over time due to mutation, natural selection, genetic recombination
- When members can no longer reproduce together, they become separate species
5. EVIDENCE OF EVOLUTION
Q17. What are the main types of evidence supporting evolution?
A17. The main types are:
- Molecular biology evidence
- Comparative anatomy evidence
- Fossil evidence
Q18. How does molecular biology provide evidence for evolution?
A18. By comparing:
- DNA nucleotide sequences
- Amino acid sequences in proteins
- Example: Beta chain of hemoglobin shows humans are closest to chimpanzees (0 amino acid differences), then gorillas (1 difference), and distant from rats (31 differences)
Q19. What does comparative anatomy reveal about evolution?
A19. Comparative anatomy shows:
- Similar bone structures in forelimbs of humans, cats, whale flippers, and bat wings
- These organs have similar internal structure but different external appearance and function
- This suggests common evolutionary origin (homologous structures)
Q20. How do fossils provide evidence for evolution?
A20. Fossils provide evidence by showing:
- Evolution is a gradual process (horse ancestors had shorter legs)
- Connecting links between species (Archaeopteryx has features of both reptiles and birds)
- Many species that lived in the past are now extinct (dinosaurs, mammoths)
6. HUMAN EVOLUTION
Q21. What are the main characteristics of primates?
A21. Common characteristics include:
- Opposable thumb
- Binocular vision
- Large brain relative to body size
- Social behavior
Q22. What are the two main categories of Anthropoidea?
A22. The two categories are:
- Cercopithecoidea: Monkeys
- Hominoidea: Apes and humans
Q23. List the stages in human evolution with their characteristics.
A23.
Q25. How did brain development influence human evolution?
A25. Brain development enabled:
- Complex social behavior
- Tool making and use
- Language development
- Higher-level cognitive functions
- Adaptation to changing environments
- Cultural development
- Advanced technology use
Part B: Human Nervous System
1. NEURONS
Q26. What are neurons and what is their function?
A26. Neurons (nerve cells) are the basic building blocks of the nervous system. They are specialized cells capable of receiving stimuli from surroundings and forming suitable messages.
Q27. Describe the structure of a neuron.
A27. A neuron consists of:
- Cell body (Cyton): Contains nucleus, cytoplasm, and organelles
- Dendrons: Fine fibers from cell body with branches called dendrites
- Axon: Longest fiber from cell body with branches called axonites
- Synaptic knob: Knob-like structure at axonite tip containing neurotransmitters
Q28. What are neuroglial cells and their functions?
A28. Neuroglial cells make up more than half of the brain and spinal cord. They cannot receive stimuli or transmit messages but perform supporting functions:
- Provide nutrition to neurons
- Eliminate wastes
- Act as defense cells
- Form myelin sheath (oligodendrocytes in CNS, Schwann cells in PNS)
Q29. What is myelin sheath and its functions?
A29. Myelin sheath is a layer of shiny white fat (myelin) covering some axons. Functions:
- Increases speed of message transmission by acting as insulator
- Provides nourishment to neurons
- Protects axons from external injuries
Q30. Differentiate between white matter and grey matter.
A30.
- White matter: Parts of brain/spinal cord where myelinated neurons are abundant
- Grey matter: Parts where cell bodies and unmyelinated parts of neurons are present
2. NERVOUS SYSTEM ORGANIZATION
Q31. What are the two main divisions of the nervous system?
A31. The nervous system is divided into:
- Central Nervous System (CNS): Brain and spinal cord
- Peripheral Nervous System (PNS): 12 pairs of cranial nerves, 31 pairs of spinal nerves, receptors, and nerve ganglia
Q32. How are the brain and spinal cord protected?
A32. Protection is provided by:
- Meninges: Three-layered covering
- Cerebrospinal fluid: Fills spaces between meninges, brain cavities, and spinal cord central canal
- Functions: provides oxygen/nutrients, eliminates wastes, regulates pressure, protects from injuries
Q33. What are the main parts of the brain and their functions?
A33.
Q34. Describe the structure and function of the spinal cord.
A34. The spinal cord:
- Continuation of medulla oblongata
- Has grey matter (inside) and white matter (outside)
- Dorsal root: Transmits messages from body to spinal cord
- Ventral root: Transmits instructions from spinal cord to body
- Central canal: Filled with cerebrospinal fluid
3. NERVE IMPULSE TRANSMISSION
Q35. What are nerve impulses and how are they transmitted?
A35. Nerve impulses are electrical messages transmitted through neurons:
- Neurons have electric charge (negative inside, positive outside)
- When stimulated, positive ions enter, causing temporary charge variation
- This electrical change travels along the neuron as an impulse
Q36. What is a synapse and how does it work?
A36. A synapse is the junction where impulses transfer from one neuron to another:
- Synaptic knob: Contains neurotransmitter vesicles
- Synaptic cleft: Small gap between neurons
- Post-synaptic membrane: Contains receptors for neurotransmitters
- Process: Impulse reaches synaptic knob → neurotransmitters released → bind to receptors → stimulate next neuron
Q37. What makes the human brain unique?
A37. The human neocortex (six-layered cerebral cortex) contains approximately 16 billion neurons, each forming about 7000 synapses. This enables advanced mental processes like thinking, decision-making, learning, and memory.
4. TYPES OF NEURONS AND NERVES
Q38. What are the three types of neurons?
A38.
- Sensory neurons: Transmit messages from receptors to CNS
- Motor neurons: Transmit instructions from CNS to organs
- Inter neurons: Connect sensory and motor neurons within CNS
Q39. What are the types of nerves?
A39.
- Sensory nerves: Made of sensory neurons
- Motor nerves: Made of motor neurons; transmit instructions to organs
- Mixed nerves: Contain both sensory and motor neurons
5. AUTONOMIC NERVOUS SYSTEM
Q40. What is the autonomic nervous system?
A40. The autonomic nervous system is part of the PNS that regulates body activities automatically. It has two divisions:
- Sympathetic system: Prepares body for emergency situations
- Parasympathetic system: Prepares body for relaxation and routine functions
Q41. Compare sympathetic and parasympathetic systems.
A41.
Q42. What are reflex actions?
A42. Reflex actions are spontaneous, involuntary reactions to stimuli that can originate from either the spinal cord or brain.
Q43. What is a reflex arc?
A43. A reflex arc is the pathway through which impulses are transmitted in a reflex action, consisting of:
- Receptor
- Sensory neuron
- Inter neuron (in CNS)
- Motor neuron
- Effector organ (muscle/gland)
Q44. What is the significance of reflex actions?
A44. Reflex actions:
- Provide rapid responses to potentially harmful stimuli
- Protect the body from injury
- Occur without conscious control
- Save time in emergency situations
7. NERVOUS SYSTEM EVOLUTION
Q45. How does nervous system complexity vary among organisms?
A45.
- Hydra: Simple neural network with no control center
- Planaria: Pair of nerve ganglia in head region for coordination
- Insects: Clear brain development with paired ganglia in each segment
- Humans: Highly complex brain with neocortex enabling advanced cognitive functions
Q46. Why is nervous system evolution significant?
A46. Evolution of the nervous system:
- Enables organisms to adapt to diverse environments
- Facilitates survival through better response to stimuli
- In humans, led to dominance over nature through cognitive and technological progress
- Enables unique abilities like language, intelligence, and creativity
8. NERVOUS SYSTEM HEALTH
Q47. What precautions should be taken for nervous system health?
A47. Important precautions include:
- Use helmets and seat belts while driving/riding
- Take safety measures during sports
- Avoid swimming in stagnant water (infection risk)
- Use safety equipment in high-risk jobs
- Avoid smoking, alcohol, and drugs
- Exercise regularly
- Get adequate sleep (8-10 hours daily)
- Maintain good nutrition