Double fertilization means that a. flowers must be pollinated twice to yield fruits and seeds. b. every egg must receive two sperm to produce an embryo. c. one sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei. d. every sperm has two nuclei.

Verified step by step guidance

1. Step 1: Understand the concept of double fertilization. In angiosperms (flowering plants), double fertilization is a process that involves the joining of a female gametophyte (also called the egg or ovule) with two male gametes (sperm).
2. Step 2: Analyze the options. Option a suggests that flowers need to be pollinated twice to yield fruits and seeds, which is not accurate. Double fertilization doesn't mean multiple pollinations. Option b suggests that every egg must receive two sperm to produce an embryo, which is also not accurate. In double fertilization, one sperm fertilizes the egg to form the zygote, and the other sperm fertilizes the polar nuclei to form the endosperm, not the embryo. Option d suggests that every sperm has two nuclei, which is not accurate. Each sperm cell has one nucleus.
3. Step 3: Based on the analysis, option c is the most accurate. One sperm is needed to fertilize the egg, forming the zygote which develops into the embryo. A second sperm is needed to fertilize the polar nuclei, forming the endosperm which provides nutrients to the developing embryo.
4. Step 4: Therefore, the correct answer is c. One sperm is needed to fertilize the egg, and a second sperm is needed to fertilize the polar nuclei.
5. Step 5: Remember, double fertilization is a unique process to angiosperms and results in the formation of a diploid zygote and a triploid endosperm.

Key Concepts

Double Fertilization

Double fertilization is a unique process in angiosperms (flowering plants) where one sperm cell fertilizes the egg cell to form the zygote, while another sperm cell fuses with two polar nuclei to form the triploid endosperm. This endosperm serves as a nutrient source for the developing embryo, ensuring its growth and development.

Angiosperms

Angiosperms are a group of plants that produce flowers and seeds enclosed within a fruit. They are the most diverse group of land plants and play a crucial role in ecosystems and agriculture. Understanding their reproductive strategies, including double fertilization, is essential for studying plant biology and evolution.

Pollination

Pollination is the transfer of pollen from the male anther of a flower to the female stigma. It is a critical step in the reproductive process of flowering plants, leading to fertilization. While double fertilization involves the fusion of gametes, successful pollination is necessary for this process to occur, highlighting the interconnectedness of these reproductive mechanisms.