B2.3 Common Systems Flashcards
Evaluate the evidence the fossil record provides for evolution
The fossil record is the history of life on Earth as sown by fossils. It suggests that many organisms have changed gradually through time, they have evolved. However ten fossil record has many gals in it because of soft tissue decay, destroyed parts or fossils buried too deep to find. These gaps mean that scientists have to interpret the incomplete data, which can lead to different interpretations of fossils which do not align.
How does the anatomy of the pentadactyl limb provide evidence for evolution?
Most vertebrates have limbs, which have very similarly constructed bones. Fossil ancestors, both with limbs and limbless have the same basic pentadactyl limb which vertebrates have today, suggesting that all vertebrates evolved from one common ancestor.
Structure of the pentadactyl limb:
Humerus Radius Ulna Carpals Phalanges
What is growth?
Growth is when an organism gets bigger in terms of size, mass or length.
What is a percentile?
The value of a variable which falls below a certain percentage of all of the population.
What is the difference between something getting bigger and something growing?
Growing involves the replication of cells and them getting bigger.
How do plants grow?
Plants have special cells called meristems just behind the tips of their roots and shoots where the cells divide. Once the cells have divided they elongate, resulting in growth.
As the plant matures the older meristem cells differentiate into any type of plant cell. For example a meristem in a shoot cell can become a leaf cell containing chlorophyll.
How do animals grow?
Animal cells also divide, but growth stops when the animals reaches adulthood. In an animal cells which can differentiate are called stem cells. These cells develop into specialised tissues and organs in an embryo, whereas adult stem cells can only really differentiate into blood cells are skeletal tissues, which is why humans cannot regrow limbs.
What are the main components of blood?
Plasma
Red blood cells
White blood cells
Platelets.
What is the role of the plasma?
Plasma is a yellow liquid which transports dissolved food substances, carbon dioxide, hormones etc.
What is the role of the red blood cells?
Red blood cells contain haemoglobin which can combine reversibly with oxygen to form oxyhemoglobin. Red blood cells are bioconcave disks which gives them a large surface area to volume ratio. They also have no nuclei to allow for the maximum space for oxygen.
What is the role of the white blood cells?
Some white blood cells make antibodies, which are proteins that bind with pathogens and destroy them other white blood cells surround and destroy any other foreign cells. All white blood cells have a nucleus.
What is the role of platelets?
Platelets are tiny fragments of cells, which make blood clot if you cut yourself. The clot dries and forms a scan, stopping microorganisms from getting into the body.
What is an organ?
An organ is group of tissues working together to perform an particular task.
Describe the path blood takes thought the heart.
Deoxygenated blood enters the heart through the vena cava. First of all it enters the right atrium, which contracts when it is full, sending the blood through valves and into the right ventricle. When the ventricle is full, the blood goes through more valves and into the the pulmonary vein and then the lungs. Then the blood comes back through the pulmonary artery and into the left atrium. it then goes through valves into the leftventricle and into the aorta, which transports oxygenated blood around the body.
What do the veins do?
The veins carry deoxygenated blood to the heart. They are wide and have thin must’ve layers so that the blood flows ate a low pressure.
What do the arteries do?
The arteries carry oxygenated blood away from the heart. They have a tick layer of muscle and a tough connective tissue so that the blood flows under high pressure.
What do the capillaries do?
Capillaries allow blood to diffuse into and out of them because they have very thin walls.
Is Anna the best person ever?
Yes, of course, how could you think any differently 🤗😃🤓🙄
What are fossils?
Fossils are preserved races or remains of organisms that lived thousands or millions of years ago.
What is digestion?
The process by which food is broken down. It can be mechanical (chewing) or chemical.
What is the alimentary canal?
A muscular tube running brought the body from mouth to anus.
What does the mouth do during digestion?
The food is taken into the body through the mouth. During chewing teeth break down the food into small pieces, increasing the surface area on which digestion can take place. The tongue helps to form the food into a ball called a bolus. The bolus gets covered in saliva making it easier to swallow. It also contains an enzyme which starts to break down the starch in food.
What does the oesophagus do during digestion?
The oesophagus is a muscular tube between the mouth and the stomach. The muscles contract in waves to push the food down into the stomach. This is called peristalsis.
