What is a purine and a pyrimidine? Name them.

Answer:

Purines and Pyrimidines are nitrogenous bases that make up the two different kinds of nucleotide bases in DNA and RNA. The two-carbon nitrogen ring bases (adenine and guanine) are purines, while the one-carbon nitrogen ring bases (thymine and cytosine) are pyrimidines.

Explanation:

Which is a result of selective breeding?
a. Large seedless watermelons that consumer demand.
b. Oranges that are all different sizes and colors.
c. An insect that can carry ten times its body weight.
d. A bird that catch prey with its beak.

How do normal faults differ from reverse faults?​

how does cell division prove the cell theory

When did Cherokee pepole first interact with Europeinanes
A. The 1500s
B. The 1600s
C. The 1700s
D. The 1800s

what could be done in terms of genetic engineering to minimize the chance of farmed raised fish from breeding with wild fish

Fermentation produces ___ ATP, which cell Respiration produces well over 30 ATP

A. 40
B. Zero
C.2
D.10

Water as deep as ___ is still affected by the wind at the Earth’s surface
A) 60 m B) 250 C) 400 m D) 700 m

This is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. It is often used to refer to the hooked structures found on arthropods.

Which of the following shows a reduction of chromosomes by half?

Choose all the answers that apply.

In a balanced ecosystem the number of _____.

producers is greater than the number of consumers
consumers is greater than the number of producers
primary consumers is greater than the number of secondary consumers
secondary consumers is greater than the number of tertiary consumers
tertiary consumers is greater than the number of primary consumers

why have diseases and many other bacterial diseases decreased over the last 100 years?

Please help with this

HELP ASAP i need this to pass my grade

this is for science, and if i get the questions right, I pass, but the teacher never taught us the lesson, idrk y. so i really need help:( Im giving away 11 points so please give me your best answers ;)



1. As an astronaut travels from the surface of Earth to a position that is four times as far away from the center of Earth, based on the Law of Gravity which of the following statement is true?



a. mass remains the same and the gravitational pull from Earth decreases


b. weight remains the same and the gravitational pull from Earth changes


c. weight increases and the gravitational pull from Earth stays the same


d. mass decreases and the gravitational pull from Earth increases


2. A satellite is sent into orbit around the Earth, In which of the following situation would the gravitational force be the greatest?



A. 1200 lb satellite orbiting 150 miles above Earth’s surface


b. 850 lb satellite orbiting 150 miles above Earth’s surface


c. 850 lb satellite orbiting 1500 miles above Earth’s surface


d. 1200 lb satellite orbiting 1500 miles above Earth’s surface



3. High and low tides are the regular pattern of rising and sinking ocean-water levels. They are caused when the sun’s gravity and the moon’s gravity pull on ocean water. The moon’s gravity has a greater effect on Earth’s oceans than the sun’s gravity. Why would the moon have a greater effect than the sun?



a. The moon has less mass than the sun.


b. The moon is closer to Earth than the sun.


c. The moon is not as hot as the sun.


d. The moon has less mass than Earth.




4. Which statement about the universality of gravity is false?



a. The gravitational force between two objects depends only on their masses.


b. Any two objects that have mass also have a force of gravity acting between them, no matter how far apart they are.


c. The gravitational force between two objects increases if the objects move closer together.


d. The gravitational force between two objects increases if mass is added to one object.

i need some help plz​

How does an enzyme influence a chemical reaction?

How do we create stronger evidence?
A) better observations
B) better opinions
C) better theories
D) better inference

Describe the role of ATP

1. mutations cause A. DNA screenings B. genetic finger prints C. genetic disorders D. protein synthesis

Which fuel source gives energy to all the activities of cells in all organisms on earth?

glucose

DNA

ATP

protein

A group of tissues that join together to perform a specific function is___?​

I WILL MARK BRAINLIEST!!!!
Water has a “bent” geometry. Which explanation does not explain why?

A.Water’s oxygen has unbonded electron pairs that repel each other.
B.Water can form hydrogen bonds.
C.Electrons are evenly distributed in the water molecule.

The purpose of oxygen in the body is to serve as the

Directional selection only occurs in response to naturally occurring events.
Please select the best answer from the choices provided
Тrue
False

Explain how conservation efforts have positively impacted ecosystems.​

What sequence of events causes a dead zone?

The chemical equation below summarizes the burning of a fossil fuel.
Fossil fuel + oxygen gas →
+ water + heat
Which substance belongs in the blank in the equation?
O A. Lactic acid
O B. Carbon dioxide
O C. Nitrogen
D. Ammonia

Which of the following is a nonrenewable resource?
A. Solar
O B. Biomass
O C. Petroleum
D. Hydropower

Which statements correctly describe Arizona’s legislative branch? Check all that apply.

The House is made up of 30 members.
The Senate is made up of 30 members.
The House has 16 standing committees.
Bills passed by the House go directly to the Governor.
Members are elected by Arizona’s citizens.

Which of the following is not a sedimentary structure?
A. Mud crack
B. Ripple mark
C. Batholith

Which statements describe floods and wildfires? Check all that apply.
(Select all that apply)
A.Both are natural hazards that affect Florida.
B.Both may affect coastal and inland regions.
C.Both are caused by drought conditions.
D.Both are made worse by the presence of muck
E.Both may be caused by thunderstorms.
F.Both may cause property destruction.