The two nuclei contained in the germinating pollen grain are

Analyze the question: It asks which two nuclei are found in a germinating pollen grain in flowering plants.

Concept: A mature pollen grain contains two cells/nuclei:

• The generative nucleus, which divides by mitosis to form two male gametes (sperm nuclei).
• The tube nucleus (also called the vegetative nucleus), which controls growth of the pollen tube down the style to the ovule.

When the pollen grain lands on the stigma and germinates, it absorbs sugary fluid, and the tube nucleus directs the pollen tube's growth. The generative nucleus follows the tube and divides to give two male gametes.

Checking the options:

• A. Egg and palisade: the egg is in the ovule, and palisade is a leaf tissue. Wrong.
• B. Generative and sperm: sperm nuclei come from dividing the generative nucleus later, so they are not the original two. In some books this appears as a distractor. Wrong.
• C. Generative and tube: this matches exactly. Correct.
• D. Spongy and tube: spongy is a leaf mesophyll tissue. Wrong.
• E. Tube and cellular: "cellular" is not a pollen nucleus. Wrong.

Answer: The two nuclei in a germinating pollen grain are the generative nucleus and the tube nucleus, which is option C.

Tip: Remember "G and T": the Generative nucleus makes the Gametes, and the Tube nucleus controls the pollen Tube.