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irina1246 [14]
3 years ago
13

What important event in animal evolution marks the beginning of the Cambrian period?

Biology
1 answer:
Alenkinab [10]3 years ago
3 0

The appearance of fossils would the the answer.

Although there has been some scientific debate about what fossil strata should mark the beginning of this period, the "International Geological Congress" determined that the Cambrian period was approximately 543 million years ago of which the first appearance in the fossil record of worms that made horizontal burrows was discovered.

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​____ allow bacteria to join together to transfer genes.
anzhelika [568]
The answer is pilus. This structure joins two bacteria of same species and allow exchange of genetic material in a process called horizontal gene transfer (conjugation). The plasmid of one of the bacteria (the mobile plasmid) is nicked once and the strand moves through the pillus to the other bacteria. It combines with the other plasmid or chromosome to for recombinant dna.
7 0
3 years ago
A 35-year-old woman is 1 day postpartum. she is reporting moderate perineal pain after giving birth and would like to clean the
Ainat [17]

A sitz bath  

A sitz bath method of bathing is most appropriate for this client .

A sitz bath is a warm, superficial method of bathing that cleanses the perineum (region between the genital area and the anus). The sitz bath is used when an individual recently give birth or when having discomfort from hemorrhoids. The sitz bath’s warm water promotes healing as it raises blood flow to the perineum. It also provides relief from pain, itching or irritation in the genital area.


5 0
3 years ago
In humans, the quadriceps muscle is a skeletal leg muscle under voluntary control. As such, it contracts in response to signals
Masja [62]

Answer:

The correct answer is - operation of reflex arc.

Explanation:

The reflex arc is a unique and special type of neural pathway that starts with a sensory neuron and ends with a motor neuron. In this operation sensory neuron acts as the receptor and motor neuron is effector. This type of neural circuit helps in faster response.

Voluntary muscles like quadriceps muscle are normally in control voluntarily however, such muscle may contract involuntary due to reflex arc. This type of contraction takes place before the signal has even reached the brain.

In this response the sensory neuron takes the signal to the spinal cord and then motor neuron to the effector muscle for faster response.

Thus, the correct answer is - operation of reflex arc.

8 0
3 years ago
What is the last stage of river flow
Dovator [93]
I believe the answer is delta.
8 0
3 years ago
Which image in the onion root tip is an example of metaphase
Pachacha [2.7K]

Answer:

If any of the pictures represent the picture I attached or have any similar properties to it, that is most likely the answer.

Explanation:

Hope this helped :)

8 0
2 years ago
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