What is the size of ribosomes found in prokaryotic cells?
A. 70S
B. 50S
C. 60S
D. 80S
Answer: Option A
Solution (By JKExamLibrary)
Prokaryotic cells contain 70S ribosomes, which are composed of a 50S large subunit and a 30S small subunit. The 'S' stands for Svedberg units, a measure of sedimentation rate. Eukaryotic cytoplasm contains 80S ribosomes, though their mitochondria and chloroplasts contain 70S ribosomes.
Explanation:
The chorion is the outermost membrane surrounding the embryo. It forms chorionic villi that interdigitate with maternal uterine tissue to form the placenta, facilitating nutrient and gas exchange. The amnion surrounds the embryo, forming a fluid-filled cavity. The yolk sac is involved in early nutrition, allantois forms part of the umbilical cord. The chorion is derived from trophoblast and extraembryonic mesoderm.
Explanation:
Filariasis, commonly known as elephantiasis due to the severe swelling of limbs and genitals, is caused by filarial worms like Wuchereria bancrofti and Wuchereria malayi. These thread-like nematodes are transmitted by the bite of infected Culex mosquitoes. The adult worms lodge in the lymphatic vessels, causing chronic inflammation and blockage.
Explanation:
Fossils provide a record of past life, showing changes. Homologous organs share common anatomy, Darwin proposed natural selection, Lamarck inheritance of acquired characters, natural selection can but not always lead to speciation.
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