Answer:
Explanation:
The cell membrane separates the cell from the outer environment. The extracellular fluid contains the sodium ions (Na+), chloride ions (Cl-), while intracellular fluid contains potassium (K +) and negative anions.
The potential difference arises when the membrane is selectively permeable to some ions. The resting potential is -70mV.
When the neurons get excited, the sodium ions start to enter by sodium channels.
Now there are more positive ions inside the cell membrane. It disturbs the resting potential i.e. -70mV. This stage is known as depolarization.
When the inside environment of the cell is more positively charged, the potassium ions start to move out of the cell. It goes out by the voltage-gated channels. Thus resting stage is maintained and it is known as repolarization.
But the initial stability of the cell membrane has to be maintained. To restore the resting stage, the sodium ions start to move out of the membrane and potassium ions enter into the cells again. This is an active transport and has done by the Na+ - K+ pump. Here 3 sodium ions move out and 2 potassium ions pumped into the cell through the plasma membrane.
Thus the resting potential regains. The potassium ions come back into the cells against the concentration gradient and ATP provides the energy for this phenomena.
Answer: 75% of the plants are purple and 25% are white. The phenotypic ratio can be expressed as 3:1.
Explanation:
Heterozygous means that its genotype has two distinct alleles, i.e. a dominant and a recessive one. So the genotype of the plants is Pp, and each plant has two alleles since<u> they are diploid organisms, which have two copies of each gene.
</u>
<u>Each plant produces gametes, which are haploids cells. That is, they only have one copy of each gene (one allele)</u>. So, the gametes produced by Pp have a P or p genotype. During fertilization, the maternal and paternal gamete are fused to form a diploid zygote where their genotype will have one allele from the father and one from the mother.
By making this monohybrid cross, we cross the gametes of each parent in the punnett square (see picture)
In the offspring, we see one PP genotype (homozygous dominant), two Pp genotypes (heterozygous) and one pp genotype (homozygous recessive). <u>Since we know the P allele is dominant and it codes for purple color, a genotype only needs one P allele to express that phenotype</u>. So Pp and PP organisms are purple, and only pp is white. That means 75% of the plants are purple and 25% are white. The phenotypic ratio can be expressed as 3:1.
Answer:
Indivisuals with producing an abnormal form of extracellular protein fibrillin are suffering from Marfan syndrome ehich is caused by genetic mutation in the FBN1 gene.
Explanation:
Gene mutations in FBN1 gene results in the production of an abnormal extracellular matrix fibrillin-1 protein that cannot function properly. These gene mutations basically reduce the amount of fibrillin-1 produced by the cell, alter the structure of fibrillin-1, or causes the impairment of the transport of fibrillin-1 out of the cell.
As a result, protein is poorly incorporated into extracellular matrix. Hence, indivisuals with Marfan syndrome present following symptoms
Tall stature.
Disproportionately long arms, legs and fingers.
Sternum either protrudes outward or dips inward.
Arched palate and crowded teeth.
Heart murmurs.
Extreme nearsightedness.
<span>1) Malthus</span> Hutton influenced darwins idea
4) <span>4. Darwin concluded that if humans could influence an offspring's traits, so could nature.</span>
Answer:
auditory ossicles
Explanation:
In reptiles, the eardrum is connected to the inner ear via a single bone, the columella, while the upper and lower jaws contain several bones not found in mammals. Over the course of the evolution of mammals, one bone from the lower and one from the upper jaw (the articular and quadrate bones) lost their purpose in the jaw joint and were put to new use in the middle ear, connecting to the existing stapes bone and forming a chain of three bones, the ossicles, which transmit sounds more efficiently
