Answer:
The correct answer is B.
Explanation:
Option A is wrong. Mammals were not the prominent species before the extinction of dinosaurs because the mammal species that lived during the dinosaurs' era were so small that they only weighed several grams and occupied small areas as their habitats.
Option C is wrong. As dinosaurs became extinct, reptiles and "birds" remained as their descendant which evolved to some of the species that we know today.
Option D is wrong. Pangea started to break up to form the geographic isolation for the diversion of many species around 175 million years ago.
So the correct answer is B. Massive extinction disrupts and changes the food chain in such a big way that it triggers a domino effect that leads to species adapting to their new environment and diversifying thus forming new species in the process.
I hope this answer helps.
Answer:
30
Explanation:
The seed of an angiosperm is formed as a result of fertilization (fusion of sperm in pollens and the ova from ovary). According to the question, the cells of the seed which will grow into the plant contains 20 chromosomes. Seeds of angiosperms contain a tissue called ENDOSPERM that forms as a result of the unique DOUBLE FERTILIZATION in angiosperms. It occurs when one haploid sperm cell fuses with two haploid polar nuclei to form a triploid endospermic structure that serves as food for the growing embryo in the seed.
Now based on the above explanation, the diploid plant cell with 20 chromosomes will have 10 chromosomes (half as much) in its gametes as a result of meiosis. This 10 chromosomes in each gamete (sperm and ovum) fuses to form a diploid zygote with 20 chromosomes, while one haploid sperm cell (10 chromosomes) also fuses with two haploid polar nuclei (10 chromosomes each) to form a triploid endosperm with 30 chromosomes i.e. 10+10+10.
Answer: B and D
Explanation: We can break down why the correct answers are choices B and D by understanding why A and C are incorrect.
Option A states that active transport utilizes channel proteins, and facilitated diffusion utilizes carrier proteins. This is incorrect. Active transport involves carrier proteins, and facilitated diffusion involves channel proteins. Carrier proteins are different from channel proteins in that, while channel proteins can only facilitate the passive diffusion of ions into or out of the cell along their concentration gradient, carrier proteins can also use ATP to move ions in or out of the cell against their concentration gradient.
This brings us to why option C is also incorrect. Option C states that both processes require the input of energy in the form of ATP. While active transport requires the use of ATP to transport ions with or against their concentration gradient, facilitated diffusion does not. This is easily remembered when we consider that active transport is called *active* transport because the cell is *actively* using energy to transport ions.
Hope this helped.
They are different from each other because ones in forest and ones in the desert
The act of clapping your hands out in front of you with your elbows fully extended is achieved by contracting the pectoralis major muscles.
The pectoralis major muscle is a thick, large fan-shaped muscle that is located in the chest area of the human body. The pectoralis major is the most superficial muscle in the chest area and its functions is associated with the movement and rotation of the shoulder joint. Body movements such as extending the arm across the front part of the body, lowering the arm to the back part of the body, and rotating the upper arm in an inward manner are achieved by the pectoralis major muscles.
