Answer:
Mesopelagic zone
Explanation:
The Mesopelagic zone, also referred to as the Twilight zone, is the second oceanic zone from the top, lying just bellow the Epipelagic zone. It is occupying the waters at depths between 200 meters and 1,000 meters. The sunlight is only managing to reach the top few meters of this zone, while the rest is not receiving any sunlight, thus this zone is not supporting the plant species because they need sunlight for the process of photosynthesis. There are lot of animal species that live in this zone though, and they are ll very well adapted for it, often having hard shells or heavily scaled bodies, larger lungs and heart, and very well developed gills. Some of the animals that live in here are the crabs and the clams. They have developed all the needed characteristics to live in this zone. Because they are prey to lot of larger animals, both the crabs and the clams have started to use the soft sediments at the bottom as cover, digging themselves below it, and mostly managing to evade trouble and end up as food for the other species.
Answer: Only options A, B, C and D are true statements
A) One sperm fuses with an egg while the other sperm fuses with the polar nuclei.
B) It results in the formation of a diploid embryo and triploid endosperm.
C) Both sperms involved in double fertilization form within the same pollen tube.
- The diploid nucleus resulting from the second fertilization undergoes meiosis to form the endosperm.
Explanation:
Double fertilization is a process that occurs in only flowering plants. It involves the following:
- A pollen grain produces TWO male gametes
- one male gamete fertilize the egg to form a zygote that is DIPLOID (with two basic sets of chromosomes)
- the second male gamete fuses with another cell named POLAR NUCLEI, to form endosperm (the food storing tissue) in the seed. The endosperm formed is TRIPLOID ( it has three sets of chromosomes), having undergone reductive division - meiosis
Thus, the options A, B, C and D are true statements
