Human Body: Nervous System, Hormones, Reproduction and Genetics
Human Body: Nervous System, Hormones, Reproduction and Genetics
Control and continuity of life are covered here: the brain and nerves control the body quickly, hormones control it slowly, and reproduction and genetics pass traits to the next generation. NTPC asks the job of each brain part, which gland makes which hormone, Mendel's work and how sex is determined.
1. Nervous System
| Part | Function |
|---|---|
| Cerebrum | Largest part; thinking, memory, intelligence, voluntary actions |
| Cerebellum | Balance and posture, coordination of movements |
| Medulla oblongata | Involuntary actions: heartbeat, breathing, vomiting |
| Hypothalamus | Body temperature, hunger, thirst |
| Spinal cord | Reflex actions |
| Neuron | Longest cell in the body; dendrite, cell body, axon |
| Synapse | Gap between neurons, crossed by chemical messengers |
2. Endocrine Glands and Hormones
| Gland | Hormone | Role |
|---|---|---|
| Pituitary | Growth hormone and others | Master gland; excess growth hormone causes gigantism |
| Thyroid | Thyroxine | Metabolism; needs iodine; deficiency causes goitre |
| Pancreas (islets of Langerhans) | Insulin and glucagon | Insulin lowers blood sugar; its deficiency causes diabetes |
| Adrenal | Adrenaline | Fight or flight; emergency hormone |
| Testis | Testosterone | Male characters |
| Ovary | Oestrogen, progesterone | Female characters |
| Pineal | Melatonin | Sleep cycle |
3. Reproduction and Genetics
| Item | Fact |
|---|---|
| Asexual reproduction | Binary fission (amoeba), budding (yeast, hydra), vegetative propagation (potato, ginger) |
| Pollination | Transfer of pollen to the stigma |
| Fertilisation in humans | Usually in the fallopian tube (oviduct) |
| Father of genetics | Gregor Johann Mendel; experiments on pea plants |
| Monohybrid ratio | Phenotype 3 : 1 in the F₂ generation |
| Dihybrid ratio | 9 : 3 : 3 : 1 in the F₂ generation |
| Human chromosomes | 46 (23 pairs) |
| Sex determination | Mother gives X; father gives X (girl) or Y (boy), so the father's chromosome decides the sex |
| DNA structure | Double helix: Watson and Crick (1953) |
| Colour blindness, haemophilia | Sex-linked disorders carried on the X chromosome |
✗ The cerebrum controls balance | ✓ The cerebellum controls balance; the cerebrum controls thinking and memory
✗ The mother decides the sex of the child | ✓ The father's sperm carries X or Y, which decides the sex
हिंदी नोट: अनुमस्तिष्क (सेरिबेलम) संतुलन बनाए रखता है और मेडुला अनैच्छिक क्रियाएँ नियंत्रित करता है। इंसुलिन अग्न्याशय की लैंगरहैंस द्वीपिकाओं से बनता है और रक्त शर्करा घटाता है। ग्रेगर मेंडल आनुवंशिकी के जनक हैं। बच्चे का लिंग पिता के गुणसूत्र (X या Y) से तय होता है।
Exam Pointer: Verified NTPC patterns: the gland that makes insulin (July 2021 CBT-1) and the father of modern genetics (March 2021 CBT-1). Brain-part and reproduction questions are tagged syllabus-based.
Pariksha Pattern: Every Way NTPC Asks This Topic
Pattern 1: Endocrine glands and hormones
[PYQ: NTPC CBT-1 31-Jul-2021 Shift-1]
EXAM LEVEL
Q. Deficiency of which hormone causes diabetes?
Insulin, made by the islets of Langerhans in the pancreas.
Answer: Insulin
EXAMATLAS LEVEL
Q. Which gland is called the master gland, which hormone is called the emergency hormone, and which element is needed to make thyroxine?
The pituitary is the master gland because it controls other glands. Adrenaline, from the adrenal glands, is the emergency hormone. Thyroxine needs iodine.
Answer: Pituitary; adrenaline; iodine
Pattern 2: Mendel and genetics
[PYQ: NTPC CBT-1 14-Mar-2021 Shift-2]
EXAM LEVEL
Q. On which plant did Gregor Mendel carry out his experiments?
The garden pea.
Answer: Garden pea
EXAMATLAS LEVEL
Q. In a cross between pure tall and pure dwarf pea plants, what phenotype ratio appears in the F₂ generation? What is the ratio for a dihybrid cross, and who proposed the double helix model of DNA?
The monohybrid F₂ ratio is 3 tall : 1 dwarf. The dihybrid F₂ ratio is 9 : 3 : 3 : 1. Watson and Crick proposed the double helix in 1953.
Answer: 3 : 1; 9 : 3 : 3 : 1; Watson and Crick
Pattern 3: Brain and nervous system
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Which part of the brain keeps the body balanced?
The cerebellum.
Answer: Cerebellum
EXAMATLAS LEVEL
Q. Match the part with its function: cerebrum, medulla oblongata, hypothalamus, spinal cord.
The cerebrum handles thinking and memory, the medulla controls heartbeat and breathing, the hypothalamus controls body temperature, hunger and thirst, and the spinal cord manages reflex actions.
Answer: Thinking; heartbeat and breathing; temperature and hunger; reflexes
Pattern 4: Reproduction and sex determination
[Pattern: syllabus-based, PYQ-style]
EXAM LEVEL
Q. Yeast reproduces asexually mainly by which method?
Budding.
Answer: Budding
EXAMATLAS LEVEL
Q. How many chromosomes does a human cell have, and which parent's chromosome decides the sex of a child? Where does fertilisation normally take place?
46 chromosomes in 23 pairs. The father decides, since his sperm carries either X or Y while every egg carries X. Fertilisation usually takes place in the fallopian tube.
Answer: 46; father; fallopian tube
60-Second Revision
- Cerebrum thinking; cerebellum balance; medulla heartbeat and breathing.
- Pituitary master gland; insulin from pancreas; thyroxine needs iodine; adrenaline emergency.
- Mendel: pea, 3 : 1 and 9 : 3 : 3 : 1; Watson and Crick double helix.
- 46 chromosomes; XY boy, XX girl; father decides sex.