Answer:
1- Option A) describes an index fossil. Trilobite existed for a short time, but was abundant and lived in many locations.
2- Option B) Continents were once joined and have since drifted apart.
Explanation:
1) Fossils are animal and vegetable rests found in different strata of sedimentary rocks. Sedimentary layers deposit chronologically, so they are used to reflect history. They keep in each layer some of the forms of life that inhabited that area in the past. These fossils turn to be very useful while dating ages. The term Index fossils refer to those fossils that only existed in a given era or geological period during evolution.
Index fossils must:
• Be easily recognizable and distinguishable from all the other fossils
• Have lived in a relatively short geological period
• Present a wide geographic distribution
• Have lived in different sedimentary basins
• Appear in different types of rocks
• Be abundant
<em>A) Trilobite existed for a short time, but was abundant and lived in many locations. </em>The species accomplish the requirements. It is easily recognizable, had a wide geographic distribution, was abundant, and lived for a short time.
2) The tectonic plates theory states that there is a continual movement of the crust. It explains the movement of the different plates and their directions and interactions. The continental drift theory explains how these movements have been taking place since millions of years ago. When continents were together in a unique continent, many species used to inhabit it. When plates started to separate, they took some of these species that got apart by the ocean. Some species were already dead and fossilized, while some other organisms died during continental drift and got fossilized after the divergence. <em>The existence of the same fossils, placed in the same layers and of the same age, suggests that they used to inhabit the same area and died during the same time, meaning that continents were together when they got fossilized. </em>
1/4 recessive can be expected for the recessive trait of mono hybrids from the F2 generation.
Option D
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Explanation:</u></h3>
Mono hybrid cross is defined as the crossing between two plants considering the two different alleles of a particular character. It was 1st performed by Father of Genetics, Sir Gregor Mendel. The mono hybrid cross done by him considered the character tallness of garden pea plants, of which one was tall and other was short.
He crossed them to get all tall plants in 
Filial generation. Now as he self bred those plants, he got the tall and short plants in ratio of 3:1. Thus he proved that the recessive trait of mono hybrids is 
of the total population of F2 generation.
Cell
Tissue
Organ
Organ system
Organism
Brain, spinal cord, nerves
The brain controls thought, behavior, emotion, memory, and basic life functions. The brain is also the origin of control over body movement. The spinal cord connects the peripheral nervous system (PNS) to the brain; nerve impulses reaching the spinal cord through sensory neurons are transmitted up into the brain. Nerves primarily involve control and coordination of all parts of the body.
The nervous system interacts with every other organ system. For example the hypothalamus in the brain controls the pituitary gland and tells it when to produce hormones, this shows that the nervous system interacts with the endocrine system.
Hope this helps :)
Answer:
Climatology
Explanation: Climatology is the study of climate and how it changes over time. This helps people have a better understanding of the atmospheric conditions which can cause weather patterns and temperature changes over time.
