Answer:
Both biotic and abiotic factors affect the survival and reproductive success rate of fishes in an ecosystem.
The number of predators that a particular type of fish will have will influence the survival and reproductive rate of that fish. An increased number of predators will mean that the fishes will not be able to survive in that ecosystem and will be eaten up.
The number of preys will also affect the survival rate of fishes in an environment. The lesser the number of preys, the more the competition for food among species.
Abiotic factors like the concentration of salts in water will also influence the survival and reproduction of fishes. If a fish is not adapted to live in saline water conditions, then accumulation of salts in the ecosystem might destroy the whole fish species in that ecosystem.
Human activities, like the throwing of wastes into the aquatic ecosystem, drainage of fertilizers in the aquatic system can also destroy the survival and reproduction rate of a particular kind of aquatic animal species.
Explanation:
Answer:
The postsynaptic cell has many synapses with many presynaptic neurons
Explanation:
Spatial summation is a process of producing an action potential in a neuron with input from multiple presynaptic nerve cells. This process determines whether an action potential will be triggered upon reaching threshold from multiple synapses with presynaptic neurons. Summation of all inputs determines if an action potential will b generated.
Answer:
Explanation:
To calculate the recombination frequency, we have to know that 1% of recombinations = 1 map unit = 1cm. And that the maximum recombination frequency is always 50%.
The map unit is the distance between the pair of genes for which every 100 meiotic products, one of them results in a recombinant one.
So, en the exposed example:
- J and K are autosomal genes
- J and K are separated by 60 M.U.
- 60 M.U. means that there is 60% of recombination.
Cross) J K / j k x j k / j k
Gametes) JK Parental jk, jk, jk, jk
jk Parental
Jk Recombinant
jK Recombinant
One map unit equals 1% of recombination frequency. This means that every 100 meiotic products, one of them is a recombinant one.
1 M.U. -------------- 1% recombination
60 M.U. ------------ 60% recombination
30% Jk + 30% jK
100 M.U. - 60 M.U. = 40 M.U.
40M.U.--------------40 % Parental (Not recombinant)
20% JK + 20% jk
Punnet Square) JK jk Jk jK
jk JK/jk jk/jk Jk/jk jK/jk
J K / j k = 20%
j k / j k = 20%
J k / j k = 30%
j K / j k = 30%
<u>Phenylketonuria</u>
Explanation:
Phenylketonuria (PKU) is a type of a rare inherited metabolic disorder.
Etiology: PKU results from excessive accumulation of the amino acid phenylalanine in the body. Normally, phenylalanine will be converted to tyrosine (forms neurotransmitters) by the action of the enzyme phenylalanine hydroxylase.
Among people with PKU, a defect in the PAH gene which codes to synthesize this enzyme occurs which leads to the absence of this enzyme. So the phenylalanine which is normally present in dietary protein is not metabolized and gets accumulated. This gene is inherited by the child only if both the parents are with the defective PAH gene.
Symptoms: Stunted growth, behaviroral disturbances, learning difficulties, seizures, tremors etc.
Treatment: Basic treatment is to follow a diet which limits dietary sources of phenylalanine. High protein foods like meat, egg should be avoided. Children can be given PKU formula to supplement their nutritional needs.
