15. Which of the following is not an accurate description of chemical reactions? A. The rates of chemical reactions can vary. B. Chemical reactions that take in energy never need a source of energy to start. C. During chemical reactions, energy can be released or used up. D. During chemical reactions, bonds can be broken or formed.

Answers

Answer 1
Answer: The correct answer is "B".
  All chemical reactions require "activation energy". Activation energy can be thought of as kickstarting a chemical reaction. If you consider lighting a match, the match does not spontaneously combust upon its removal from the matchbox. You must kickstart the reaction by heating the chemicals in the match head. This heat is generated by the friction of rubbing the match head against the side of the box.In any case, reactions that take in energy, must take that energy from somewhere, so they absolutely need a source of energy to start, and to continue!
Answer 2
Answer: B is the correct answer I just took the test

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If an animal has long canine teeth and sharp molars it is probably aa. carnivore. b. rodent. c. deer. d. herbivore.
Which of the following clades is most likely to survive a series of catastrophic events over time? (1 point)A. A clade with a few closely related and similar species. B. A clade with a few distantly related and diverse species. C. A clade with many closely related and similar species. D. A clade with many distantly related and diverse species. 2. In the past, mass extinctions encouraged the rapid evolution of surviving species (1 point) A. by changing developmental genes. B. by making new habitats available to them. C. because they killed all organisms that had coevolved. D. because they spared all organisms that had evolved convergently. 3. The Australian flying phalanger is a marsupial flying squirrel. Its appearance, behavior, environment, and diet closely resemble those of the American flying squirrel, a placental mammal. This resemblance is most likely due to (1 point) A. adaptive radiation. B. convergent evolution. C. coevolution. D. gradualism. 4. Gradualism is a pattern of evolution in which (1 point) A. a single species evolves into several closely related species. B. several distantly related species develop similarities. C. a species evolves at a slow, steady pace. D. a species has periods of little evolution interrupted by periods of rapid evolution. 5. Mass extinction would most likely result from which of the following events? (1 point) A. A disease kills off a single species of predator within an ecosystem. B. A wildfire burns a national park. C. Global temperatures drop several degrees after several massive volcanic eruptions. D. A massive earthquake strikes North America.
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MULTIPLE CHOICE QUESTIONWhat is the test variable (independentvariable) here?The additive anti-barnacle treatmentThe number of barnacles on the boatThe amount of paint applied to the boat
What two scientists established the structure of DNA?

Skin color in a certain species of fish is inherited via a single gene with four different alleles. One fish of this type has alleles 1 and 3 (S1S

and its mate has alleles 2 and 4 (S2S4). If each allele confers a unit of color darkness such that S1 has one unit, S2 has two units, and so on, then what proportion of their offspring would be expected to have five units of color?
A) 1/4
B) 1/5
C) 1/8
D) 1/2
E) 0

Answers

The answer is D) 1/2.

If each allele confers a unit of color darkness, then only genotypes S2S3 and S1S4 will have 5 units of color darkness because in genotype S2S3 S2 will have 2 units, and S3 will have 3 units, which is 5 units in total. The similar math is for genotypes S1S4.

Now, let's cross S1S3 and S2S4:
Parents:          S1S3      x     S2S4
Offspring:  S1S2    S1S4     S2S3     S3S4

The offspring with genotype S1S2 will have 3 units of color darkness. The offspring with genotype S1S4 will have 5 units, as well as the offspring with genotype S2S3. The offspring with genotype S3S4 will have 7 units.
It can be assumed that only 2 genotypes out of 4 will have 5 units:
2/4 = 1/2.

Vanessa notices that even though her 80-year-old grandmother keeps her thermostat at 800 F, she still wears a sweater in her house. When Vanessa asks her grandmother why, her grandmother tells her she is very cold. Vanessa can’t understand this and asks you for an explanation. What would you tell her?

Answers

Answer:

As one age, the bodies become subtle to cold temperatures. This is generally due to decline in the metabolic rate. As one age, the bodies lose the tendency of producing sufficient heat to sustain the usual temperature of 98.6 degrees. In addition to this, thinning of the skin is another thing, which may contribute to the feeling of cold in older individuals.  

With age, the physical tendency of the body declines, and the body does not function as it used to earlier. A decline in temperature can make the older adults very cold, even if they are dressed warmly. There are various researchers, which shows that older individuals exhibit low body temperatures in comparison to the younger ones.  

Some of the factors that can contribute to cold sensitivity in older adults are:  

1. Poor metabolic rate

2. Loss of elasticity of the blood vessels.  

3. Low blood pressure

4. Thinning of the fat layer underneath the skin

5. Physical issues and exposure to cold water

Which would have the GREATEST effect on the rate of photosynthesis in a plant? A) oxygen level B) light intensity C) sugar concentration D) starch concentration

Answers

The correct answer is option B, Light intensity

Reason -

Light intensity plays a major role in the regulation of photosynthesis. In the absence of light a plant is unable to photosynthesize. As the plant receives light through the chlorophyll , essential chemical reactions takes place thereby releasing free electrons which keep on driving the further processes or reactions in a plant to produce food and oxygen and energy..  

The higher the light intensity, the higher is the rate of photo synthesis

Oxygen levels make no impact, they need CO2.
Sugar concentration makes no impact as that is a product.
Starch makes no impact.
Only light from the choices above is the factor in photosynthesis that could have the greatest effect as it is not a product yet a reactant

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. the evolution of the swim bladder from lungs of an ancestral fish is an example of __________.

Answers

exaptation - when a limb evolves and takes on a new function

Group of organs working together to perform a specific job?

Answers

That would be called an Organ System, like a respiratory system or a circulatory system :)

Community One is made up of 500 different species and has a total number of 5000 individuals. Community Two is made up of 100 different species and has a total number of 10,000 individuals. Which community has higher species diversity?Community One
Community Two
They both have the same species diversity
There is not enough information to determine species diversity

Answers

I think it is community one that has the higher species diversity