In the human body, the 'Midbrain' contains the superior and inferior colliculi, which are collectively known as the:
A. Corpora lutea
B. Corpora cavernosa
C. Corpora allata
D. Corpora quadrigemina
Answer: Option D
Solution (By JKSSB Mock Tests)
The midbrain (mesencephalon) is the uppermost part of the brainstem. Its dorsal surface features four rounded elevations called the corpora quadrigemina (meaning 'four bodies'). These consist of two upper, larger swellings called the superior colliculi, which are reflex centers for visual movements (like tracking moving objects), and two lower, smaller swellings called the inferior colliculi, which are part of the auditory pathway and relay sound information to the thalamus.
Explanation:
The diaphragm is a dome-shaped skeletal muscle that contracts during inspiration, flattening and increasing thoracic volume. The external intercostal muscles assist.
Explanation:
Mature mammalian red blood cells (erythrocytes) lose their nucleus and other organelles during development to maximize space for hemoglobin. Thus they are anucleate. They cannot divide or repair themselves and have a lifespan of about 120 days. Neurons, leukocytes, and hepatocytes are nucleated. RBCs obtain energy through anaerobic glycolysis.
Consider statements about mitochondria: 1. They have a single membrane. 2. They contain their own circular DNA. 3. They are the site of aerobic respiration. Which are correct?
Explanation:
Mitochondria are double-membrane-bound organelles, possessing an outer smooth membrane and a highly folded inner membrane forming cristae. They contain their own circular DNA and 70S ribosomes, making them semi-autonomous. They are the primary site of aerobic respiration and ATP production. Statement 1 is incorrect as they have two membranes.
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