The oil layer prevents the entry of air into glucouse explain why is this necssary

7th grade question (easy) look at the diagram of the food web. the arrows mean eaten by. what would happen if the number of snakes went down? answer choices are in the image.

Our planet has experienced five major extinctions in the four billion year history of life. the first, 450 million years ago, occurred shortly after the evolution of the first land-based plants and 100 million years after the cambrian explosion. the second extinction occurred 350 million years ago, causing the formation of coal forests. next earth experienced two mass extinctions during the triassic period, between 250 and 200 million years ago. the fifth mass extinction occurred 65 million years ago, ending the reptilian dominance of the earth. according to richard leakey, the sixth mass extinction is happening right now. leakey suggests that we, the human race, are the cause. each year, at our hand, approximately 50,000 species vanish from earth. he believes that man is destroying earth at a rate comparable with the impact of a giant asteroid. leakey's statistics indicate that 50% of earth's species will become extinct within the next 100 years assuming leakey's hypothesis of a sixth mass extinction to be true, how will we expect the model to change? a) a sharp spike in the graph approximately 100 million years from now b) a dip in the graph, followed by a sharp spike about 100 million years from now c) a sharp spike in the graph immediately following the "0" location of the x axis d) a plateau following the "0" mark on the x axis, followed by a gradual rise to a new peak

1. this system transports blood through the body and heart. 2. this system relates to the process by which an organism gets rid of its waste. 3.this system is responsible for movement of bones and fluids throughout the body. 4. this system receives and transmits information and responses. it depends upon electrical impulses created by the movement of charged particles. 5. this system relates to the process by which an organism replicates. sexually reproduction usually involves male cells (sperm) meeting female cells (eggs) to produce a fertilized egg or zygote. 6. this system gets oxygen to the cells of the body and rids the body of waste gases. some organisms use their skin. this is also a cell-level process. 7. this system relates to the structure and support of an organism. it is made of salts and proteins and found in vertebrate animals. 8. this is the system of organs which circulate blood around the body of most animals. 9. this system controls the glands that secrete hormones. 10. this organ system to protect the body from damage. itembank : system circulatory digestive system endocrine system excretory integumentary system muscular system nervous system reproductive system respiratory system skeletal system cardiovascular system