Which feature is found among an autosomal recessive pedigree?
a. heterozygotes have a normal phenotype.
b. affected children will have at least one affected parent.
c. heterozygotes are affected.
d. both males and females are affected with equal frequency.
e. the trait is carried on the y chromosome?

Esophageal varices are enlarged and swollen veins at the lower end of the esophagus, often associated with liver cirrhosis. Treatment options include medications, endoscopic procedures, or surgery.

Esophageal varices refer to enlarged and swollen veins at the lower end of the esophagus. These swollen veins are a serious complication of liver cirrhosis, where blood flow through the liver is obstructed, leading to increased pressure in the veins of the esophagus.

For example, when the hepatic portal vein is obstructed due to cirrhosis, blood from the digestive organs backs up and flows into smaller veins of the esophagus, causing them to swell and become varicose.

Esophageal varices can be life-threatening if they rupture, leading to severe bleeding. Treatment involves reducing the pressure in these veins through medications, endoscopic procedures, or surgery.

Scientists study both the flatworm Planaria and the roundworm Caenorhabditis elegans in laboratories, using them as test subjects, and while they may seem similar, they have some distinct internal and external differences. Flatworms (phylum Platyhelminthes) and roundworms (phylum Nematoda) differ in shape, means of locomotion, how their digestive systems function, and in the ways they are harmful to human beings. While both species are called worms, they are not closely related.

Answer: b. bog

A wetland is an ecosystem that is occupied with water either permanently or seasonally. The wetlands are distinguished from other lands or water bodies depending upon the vegetation growing here. Bog is a type of wetland. It is characterized by wet, acidic and low oxygenated soil.  The soil accumulates organic material with less organic matter decay as decomposition rate is slow in these soils.

sister chromatids lining up in the center of the cell.

A mutation is least likely to affect a cell when the mutation is reverses the order of bases in a DNA strand. when the total number of bases in a DNA sequence remain the same. Replaces a base with its complementary base and produces a codon which codes for the same amino acid as the original codon.

Final answer:

Natural selection can lead to changes in allele frequency when certain alleles provide a survival or reproductive advantage, resulting in beneficial alleles becoming more common, while disadvantageous alleles become less frequent.

Explanation:

Natural selection can lead to a change in allele frequency through the differential reproduction of individuals with certain traits. When individuals in a population have alleles that confer advantageous traits, they are more likely to survive and reproduce, passing these alleles on to the next generation. Consequently, these beneficial alleles become more common within the gene pool.

For example, let's consider the famed case of the peppered moth's coloration. Initially, most peppered moths had mottled white wings, but during the Industrial Revolution, trees became covered with soot. Moths with darker wings were less visible to predators and therefore survived longer and reproduced more. The allele for dark wing coloration increased in frequency over time. After environmental clean-up efforts, trees became cleaner again, and the mottled white allele regained prevalence as these moths had a survival advantage once more.

In summary, as certain alleles become favorable in the environment, they allow individuals to have more offspring who inherit the alleles, and over time, this can lead to these alleles increasing in frequency. Conversely, alleles that provide a disadvantage decrease in frequency.

Answer:

It depends on the weight of teen before getting pregnant.

25 to 35 pounds should be weight gain for average weight girl , for underweight girl it should be 28 to 40 pounds and 15 to 25 pounds for overweight girl.

Explanation:

Nutrition , exercise is must for healthy teen pregnancy. All essential vitamins , minerals iron , calcium , folic acid should be in the diet. Low intake of essential diet leads risk of low weight of  baby , also may be other health complications. Alcohol, smoking , drugs should avoid during pregnancy.

During pregnancy, recommended weight gain for a teenager depends on their pre-pregnancy BMI, with normal weight individuals advised to gain 25-35 pounds.

During pregnancy, a mother's body undergoes significant changes, one of which is weight gain. The recommended weight gain depends on the mother's pre-pregnancy BMI. For teenagers of normal pre-pregnancy weight, the typical recommended weight gain is about 25 to 35 pounds.

This weight gain supports both the development of the fetus and various physiological changes in the mother's body.

The statement In blood pressure measurements, the smaller bottom number is the diastolic pressure, not the systolic pressure is not true .

Blood pressure is typically recorded as a fraction, where the top number is the systolic pressure, and the bottom number is the diastolic pressure. For example, a blood pressure reading might be expressed as "120/80 mm Hg."

Systolic Pressure: This is the higher number and represents the pressure in the arteries when the heart is contracting or beating.

It reflects the force of blood against the artery walls during the heart's pumping phase.

Diastolic Pressure: This is the smaller bottom number and represents the pressure in the arteries when the heart is at rest between beats.

It indicates the minimum pressure in the circulatory system, and it reflects the resistance of the blood vessels when the heart is not actively pumping.

So, when you see a blood pressure reading, the systolic pressure is the larger top number, and the diastolic pressure is the smaller bottom number.

Both numbers are important for assessing cardiovascular health. An ideal blood pressure reading is typically considered to be around 120/80 mm Hg, but the specific target may vary based on individual health factors and guidelines.

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Final answer:

The main difference between antennae and antennules is that antennae are single, primary sensory appendages found on insects, while antennules are a secondary pair of sensory appendages found in crustaceans. Antennae are typically used for chemical sensing and sometimes sound detection, whereas antennules may be involved in more specific functions like detecting water pressure or balance.

Explanation:

The terms antennae and antennules often refer to the sensory appendages found in various arthropods, including insects and crustaceans. In insects, antennae are a pair of long, thin sensory organs located on the head, used primarily for smelling and tasting chemicals, but can also be adapted for detecting sound. These antennae can come in various shapes and sizes, serving different sensorial modalities depending on the insect species. For example, butterflies and bees utilize their antennae not only to sense chemicals but also to aid in navigation as they can detect color.

In crustaceans, antennules serve as an additional pair of sensory appendages besides the main antennae. Crustaceans typically have two pairs of antennae: the first pair are the antennules, which are often smaller and sometimes carry out more specific and sensitive functions, such as detecting changes in water pressure or balance for aquatic species, while the second pair are the larger antennae mainly used for chemical detection and touch. This distinction is part of what typifies the different body structures between crustaceans and insects.

It's also important to note that insects exhibit a wide range of specialized external structures adapted to their environment and lifestyle, such as different types of mouthparts for various feeding habits and compound eyes for vision. An example of this diversity is seen when comparing the standard fruit fly to the Antennapedia mutant, which has legs on its head instead of antennae, highlighting the role of genetics in the formation of these appendages.

Antennae and antennules are both appendages found on the heads of arthropods, particularly crustaceans and insects, and they serve sensory functions. However, they differ in their relative size, position, and specific sensory roles.

The correct explanation of the difference in structure between antennae and antennules is as follows:

Antennae are typically the larger of the two and are usually located on the second segment of the head, behind the eyes. They are often segmented and can be quite long, providing a large surface area for sensory reception. Antennae are used for detecting touch, air currents, humidity, and various chemical signals. In insects, they are also important for the detection of pheromones, which are crucial for communication and mating behaviors.

Antennules, on the other hand, are smaller and are located in front of the antennae, often between the eyes. They are usually less segmented than antennae and are more specialized for chemoreception, allowing the organism to taste and smell its environment. In aquatic crustaceans, such as crabs and shrimp, antennules are particularly important for detecting dissolved chemicals in the water, which can signal the presence of food, predators, or potential mates.

In summary, the key differences are:

1. Position: Antennules are positioned in front of the antennae, closer to the mouthparts.

2. Size: Antennules are generally smaller than antennae.

3. Segmentation: Antennules are typically less segmented than antennae.

4. Function: While both structures have sensory functions, antennules are more specialized for chemoreception, and antennae are more versatile, involved in detecting a broader range of stimuli including mechanical and chemical signals.

These structural differences reflect the specialized roles that antennae and antennules play in the sensory ecology of arthropods.

Mutations introduce new genetic variations which can enable species to adapt to environmental changes. Some mutations could be beneficial, enhancing survival, and thus spread through the population. Coevolution occurs as species continuously adapt in response to each other's adaptations.

Mutations refer to changes in an organism's DNA and function as a significant driver in their diversification. Species evolve because of the accumulation of these mutations over time. This process brings forth new genotypic and phenotypic variation. Some mutations may be harmful and thus are quickly expunged from the population through natural selection. However, others can be highly beneficial and thus proliferate through the population. A mutation's value is determined by its potency to aid an organism to survive until sexual maturity and then reproduce. In changing environments, this dynamic plays out in beneficial ways. For instance, new combinations of genes can enhance survival during environmental changes, and sexual reproduction can result in diverse phenotypes which enhance a population's survival in a shifting environment. This phenomenon helps to keep a balance in the evolutionary 'race', where organisms are continuously adapting in response to each other's adaptations, ultimately leading to coevolution.

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If two homozygous plants with contrasting traits are crossed, the expected genotypes for the offspring will be heterozygous. The dominant trait would be expressed, but they'd be carriers for the recessive trait.

The two same allele plants with contrasting traits are crossed, the expected genotypes for the offspring - heterozygous with the dominant phenotype.

The plants will have the same allele genotype for both of their chromosomes. In other words, Let assume "b" is a recessive allele for a trait and B for a dominant trait then, one plant will have the genotype "BB", and the other will have "bb."

    T     T

t    Tt    Tt

t    Tt     Tt

Thus, The two same allele plants with contrasting traits are crossed, the expected genotypes for the offspring - heterozygous with the dominant phenotype.

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Answer:

Messenger RNA carries a(n) transcript of the DNA’s instructions out of the nucleus to the ribosome.

Explanation:

so it's (A

Yellow bone marrow is the tissue in the central canal of bone that consists chiefly of fat cells. Yellow bone marrow produces fat cells, cartilage, and bones. It acquires the yellow color by carotenoids in the fat droplets and it arises from the conversion of the red bone marrows which occurs with age.