Extranuclear inheritance is due to presence of genes in-A. Mitochondria and chloroplastsB. Nucleus and mitochondriaC. Nucleus and chloroplastsD. Endoplasmic reticulum and mitochondria

The correct answer is A. Mitochondria and chloroplasts.
Extranuclear inheritance refers to the transmission of genetic material that is not found in the nucleus of the cell, but in the mitochondria and chloroplasts. This type of inheritance is also known as cytoplasmic inheritance.
1. Mitochondria and Chloroplasts:
o Both mitochondria and chloroplasts are organelles within eukaryotic cells that contain their own small circular DNA, separate from the nuclear DNA.
o These organelles replicate and pass on their DNA independently of the cell's nuclear DNA. This is why traits governed by genes in these organelles are inherited in a non-Mendelian fashion, outside the control of the nuclear genome.
2. Key Features of Extranuclear Inheritance:
o Mitochondria: Mitochondria are the powerhouses of the cell and contain their own DNA. In most organisms, mitochondrial DNA is inherited maternally, meaning it is passed from the mother to offspring, not through the father. This form of inheritance is important for traits related to cellular energy production.
o Chloroplasts: Chloroplasts, which are involved in photosynthesis in plant cells, also contain their own DNA. Similar to mitochondria, chloroplast DNA is typically inherited maternally in many plants.
3. Why the Other Options Are Incorrect:
o B. Nucleus and mitochondria: The nucleus contains the majority of the genetic material (genome), and genetic inheritance from the nucleus follows Mendelian principles. Extranuclear inheritance involves only the mitochondria and chloroplasts, not the nucleus.
o C. Nucleus and chloroplasts: While chloroplasts do exhibit extranuclear inheritance, the nucleus is not involved in extranuclear inheritance. Nuclear inheritance follows Mendelian patterns, and genetic material in the nucleus does not undergo extranuclear inheritance.
o D. Endoplasmic reticulum and mitochondria: The endoplasmic reticulum is involved in protein and lipid synthesis, but it does not contain its own DNA, and thus is not involved in extranuclear inheritance.
Extranuclear inheritance is due to the presence of genes in mitochondria and chloroplasts, making A. Mitochondria and chloroplasts the correct answer.