1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Xelga [282]
3 years ago
7

13. Natural selection is the most powerful of all the processes that change what in a

Biology
1 answer:
LiRa [457]3 years ago
3 0
It changes heritable traits and phenotypes
You might be interested in
How is it possible for one twin to get skin cancer but the other one doesn´t
tia_tia [17]

Looking at most newborn twins squirm contentedly in their cribs, you'd never guess that some were recently in peril. That's because carrying multiples raises the risks that a woman can suffer complications before she actually delivers.

Many twins are miscarried early in the pregnancy, often before a woman even knows she's pregnant. As reported in the International Journal of Fertility, only about one in eight embryos that starts as a twin is born as a twin. If they do survive, twins are usually born healthy. However, they are still more likely than other babies to have birth defects or to be born prematurely or underweight.

Carrying twins can be hard on you, too. You'll be more likely to develop pregnancy-related high blood pressure or diabetes. And there's a greater likelihood you will have a cesarean section when you deliver.

If you're carrying twins, some simple lifestyle changes and good prenatal care may help you reduce the likelihood of the following complications.

Low birth weight

Because they have to share nutrients and living space, newborn twins tend to be smaller than single babies. Even full-term twins often weigh less than 5-1/2 pounds each, making them vulnerable to a variety of health problems. You can help your babies reach a healthy size by making sure you put on enough weight during pregnancy. Try to eat 300 calories more each day than you would if you had a single baby (about 2,700 calories in total). If you had a healthy weight before pregnancy, you should aim to put on about 35 or 45 pounds.

Unequal size

Twins don't always share equally. In roughly 30 percent all twin births, one baby will be larger than the other. Some studies suggest that if one of your babies is at least 25 percent heavier than the other, one or both of them may be more likely to have breathing problems or need intensive care. Your doctor will track the growth of both your babies throughout your pregnancy. The first signs of unequal growth usually appear in the third trimester.

Twin transfusion syndrome

Twin transfusion syndrome poses a dangerous threat to identical twins who share a single placenta. It's normal for such twins to exchange blood during a pregnancy. But in about 20 percent of cases, one twin starts pumping large amounts of blood to the other twin, putting both of them at risk. In severe cases, the twin receiving the extra blood may develop heart failure while the other twin becomes dangerously anemic. Early diagnosis and treatment can slow the abnormal blood flow and lower the risk of complications.

Birth defects

Birth defects are common in twins, especially identical twins. Taking folic acid before and during pregnancy can help prevent neural tube defects. As reported in the medical journal The Lancet, however, about 10 percent of all identical twins are born with a birth defect such as a heart problem, a shortened limb, a club foot, or a dislocated hip (the conditions listed are linked to having less space in the uterus and would not be affected by folic acid.) Most of these conditions are treatable, however.

Risks to the mother

Your doctor will check you regularly throughout the pregnancy for signs of high blood pressure or diabetes. When detected early, both of these conditions can be controlled before they have a chance to threaten your pregnancy.

Special care

Carrying twins means you'll probably get extra attention from your doctor throughout your pregnancy. The doctor may suggest cutting back on activities between the 20th and 30th week of pregnancy, even if you haven't had any signs of labor. Many physicians also recommend an extra monitoring check on the babies' heart rate and movement, such as an ultrasound or nonstress test. A biophysical profile, which checks on heart rate, movement, and the amount of amniotic fluid in your body, might also be indicated. If you do go into labor prematurely, your doctor may suggest drugs to stop the labor or use corticosteroids to speed up the development of the babies' lungs.

It's possible that you may be able to deliver twins vaginally. But if the labor is difficult, the birth canal is too narrow, or one or both of the infants is in the breech position, you may have to undergo a c-section, in which the babies are delivered through an incision in your uterus. Talk to your doctor about what you can do to prepare for delivery.

Twins are a special challenge, both before birth and after. For now, your job is to stay healthy and get top-quality prenatal care. Two important people are counting on you.

Does this help lol :D

4 0
2 years ago
Read 2 more answers
Every DNA molecule is made out of molecules called?​
Anestetic [448]

Answer: Nucleotides

Explanation: DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).

3 0
3 years ago
Read 2 more answers
It is a winter day in Florida, and the temperature is 40°F in the morning. While you are walking to class, your body uses a nega
zhannawk [14.2K]

Answer:

negative feedback

Explanation:

The negative feedback system is the most common in the body, being considered by many authors the primary mechanism for the maintenance of homeostasis. It causes a negative change from the initial change, that is, a stimulus contrary to the one that led to the imbalance. In the case of the above question, when the ambient temperature increased, your body began to sweat to lower the temperature, that is, your body is trying to make a stimulus contrary to what is happening in the environment, so we can state that your body is going through a negative feedback system.

5 0
3 years ago
Kohler and lipton first discovered a growth factor (pdgf) by:
Juliette [100K]
<span>Observing that fibroblasts grew better in cell culture when blood serum was added to the growth medium instead of blood plasma. Thus proving that there was a substance in serum that made it easier for fibroblasts to grow.</span>
5 0
3 years ago
During which period did T. Rex reign?
Furkat [3]
The answer's D. Cretaceous.
3 0
3 years ago
Read 2 more answers
Other questions:
  • Several species of leopard frogs are common throughout North America, where their ranges overlap. Different species of leopard f
    6·1 answer
  • Why are globular proteins important? What are their primary functions and what are they made of?
    6·2 answers
  • What practice would probably NOT reduce the greenhouse effect? A) Increased use of aerosol spray cans. B) Reduced use of forests
    10·2 answers
  • Both aerobic and anaerobic respiration yield a net gain of ATP molecules to be used as energy for living things. The processes o
    9·1 answer
  • The cytoskeleton has several primary functions. the first and most obvious is it acts as an interior skeleton that supports the
    15·1 answer
  • Should scientists who identify genes and create new genetic engineering techniques have the right to patent their methods for th
    8·1 answer
  • 24 pts!
    14·2 answers
  • Pls !<br> Help!<br> How does the length of interphase compare to the length of cell division?
    8·1 answer
  • yo i need the answers idc if u look it up i cant tho im in school and they know if we look it up cuz they see our search history
    12·1 answer
  • I have a question for you guys
    14·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!