Characteristics of Lancelets:
Small
Elongated
Marine invertebrate
Lacks a jaw
No sense organs
Has a notochord
Example: Lamprey
Characteristics of Tunicates:
Marine invertebrate
Has an outer coat that is rubbery or hard
Has two siphons
Examples: sea squirts, salps
Answer:A. The release of calcium ions causes myosin and actin to attach to each other.
The contraction of skeletal muscles takes place by induction of a nerve impulse, which produces a movement and the interaction of the filaments containing proteins named as actin and myosin. This interaction of filaments is regulated by proteins called tropomyosin and troponin present on the actin filaments. The motor nerve causes the depolarization of the muscle membrane sarcolemma. This triggers the sarcoplasmic reticulum to release calcium ions. This calcium binds to troponin and thus allows the tropomyosine strand on the actin filament to displace so that the part of the actin where myosine head needs to be attached remain uncovered. Binding of the actin myosine filament results in contraction.
Hence, the release of calcium ions causes myosin and actin to attach to each other causes muscle contraction.
Answer:
The correct answer would be D) tissue.
In biology, the level of organisation from simplest to complex level can be summarized as:
Organelles → cells → tissues → organs → organ systems → organisms → populations →communities → ecosystem → biosphere.
It is clear that tissue is organization level that exists between cells and organs.
When similar cells are assembled together to perform specific function, the assembly or this organization is said to be the tissue.
There can be different types of tissues such as muscle tissue, nerve tissue et cetera.
Similarly, tissues arrange themselves to carry out specific function in the form of organ.
For example, heart is made up of cardiac tissue.
When cells in a body are not working properly and normally, they cause disruption in the body homeostasis.
Homeostatis is characterized as balance in the body but when there is any disturbance in the body, it breaks down the balance and cause imbalance. For example in the case of diabetes in which body fails to maintain the good amount of glucose in blood which results in imbalance the body which is why diabetic patients are asked to maintain and monitor their body sugar level to maintain homeostatis.
Answer:
The environment plays a role in a mutant allele in a population because some mutations are more beneficial to the organism than other mutations.
Explanation:
Organisms with a beneficial allele mutation will be able to pass on their genes as they reproduce. The mutation makes them <em>fit</em> for survival in their environment. Other organisms <em>without </em>the beneficial allele won't be able to pass on their genes since it will be more difficult for them to survive in their environment. Natural selection will deem that the organisms with the mutation will survive better and be able to produce offspring with the same mutation.
