Unknown Student Guide Questions Flashcards

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1
Q

What are the 3 layers separating plasma from filtrate?

A

The capillary endothelium, the basement membrane on which the capillary cells lie, and the inner layer of the Bowman’s capsule

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2
Q

Describe the inner layer of the Bowman’s capsule

A

Consists of podocytes, with foot-like processes which surround the capillaries but which have spacious gaps between them called filtration slits

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3
Q

Describe adaptations in the tubules

A

Cuboidal epithelial cells which line tubule walls have many microvilli on the side in contact with the filtrate, and infoldings of the cell surface membrane on the side next to the capillaries. These adaptations increase the S.A. for reabsorption. The cells have many mitochondria to supply ATP for active transport

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4
Q

What must a microorganism do to be pathogenic?

A

1) enter the host 2) colonise host tissue 3) evade host defences 4) cause damage to host tissue

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5
Q

What is the difference between polymorphs and macrophages?

A

Polymorphs, more abundant but short lived, remain in blood until there is an infection when they move out of capillaries to site of infection. Monocytes are blood cells that can move out of blood capillaries into surrounding tissue where they develop into macrophages

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6
Q

How are antigen-antibodies like the lock and key model?

A

For each antigen on the surface of a pathogen. there is a lymphocyte that carries a special protein receptor on its cell surface membrane that is complementary in shape.

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7
Q

Where do B cells mature?

A

In the Bone marrow

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8
Q

Where do T cells mature?

A

in the Thymus

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9
Q

What happens after lymphocytes are sensitised?

A

A specific gene is activated, mRNA synthesized and proteins are produced. These proteins are either antibodies in B cells or membrane receptors in T cells. This process takes time. The sensitised lymphocyte is then cloned by mitosis.

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10
Q

What do antibodies do?

A

Some neutralise toxins produced by bacteria, some clump or agglutinate bacteria before they are engulfed by phagocytic cells (antibodies are agglutinins), some attach to viruses to prevent entry of host cells, some destroy bacterial cell walls causing cell lysis, some antibodies attach to bacteria enabling phagocytic cells to identify them

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11
Q

What are antigens / antibodies?

A

Antigens are foreign while antibodies are produced in body by b cells

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12
Q

Why can being given the wrong blood cause agglutination?

A

Anti-a and anti-b are agglutinins

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13
Q

What is the difference between agglutination and clotting?

A

Agglutination is the sticking together of RBC, clotting involves the formation of fibrin and only involves RBC in that they might become enmeshed in network of fibres

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14
Q

Outline auxin action

A

Produced in cells of the apical meristem. diffuse down shoot towards zone of elongation. bind to specific receptors on cell surface membrane of newly formed cells. this causes membrane pumps to move hydrogen ions out into cellulose cell wall. the acidification of cell walls activates agents which loosen the linkages between cellulose microfibrils, allowing slippage between them, and making cell wall more flexible. the cells absorb water by osmosis and the flexible cell walls allow the cells to expand as the water exerts increased hydrostatic pressure against them. the more auxin that is received in the zone of elongation, the more this effect allows cells to expand

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15
Q

What does positively phototrophic mean

A

Grows towards light

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16
Q

How is the photoperiod measured?

A

By phytochrome pigments, P660 and P730

17
Q

What wavelength does P660 absorb?

A

red light

18
Q

What wavelength does P730 absorb?

A

far-red light

19
Q

Why is P660 converted to P730 in the day time?

A

Sunlight contains more light of wavelength 660nm than 730nm therefore P660 is converted to P730

20
Q

What are the 3 parts of a neurone?

A

A cell body (centron) which contains the nucleus and other organelles, and has a number of cytoplasmic extensions
Extensions called dendrons (or dendrites if they’re small) which transmit impulses to the cell body
Extensions called axons which transmit impulses away from the cell body and terminate in synaptic bulb.

21
Q

What is the resting potential?

A

-70 mV (millivolts) (negative 70)

22
Q

What is the critical potential difference?

A

Around -55mV

23
Q

What is saltatory conduction?

A

The action potential jumps from one node of ranvier to the next

24
Q

What are rods sensitive to?

A

dim light

25
Q

What are cones sensitive to?

A

bright light, but are able to discriminate fine detail and distinguish different wavelengths of light/

26
Q

Where are cones concentrated?

A

At the fovea, the centre of the retina.

27
Q

Where are rods found?

A

Around the periphery of the retina

28
Q

What do rods and cones synapse with

A

with bipolar neurones which in turn synapse with neurones of optic nerve

29
Q

What is retinal convergence?

A

many rods synapse with each bipolar neurone and many cells connect with each neurone of the optic nerve

30
Q

How does light travel in the retina?

A

Light passes through the neurones before reaching the outer segments of the rods and cones. The consequence of this is that for the neurones to leave the eye they must pass through the layer of photoreceptors creating an area devoid of receptors - the blind spot

31
Q

What happens when light hit rhodopsin?

A

rhodopsin breaks down into retinal and opsin. This results in a change in the membrane potential of the rod cell and creates a generator potential. This causes a change in the membrane potential of the neighboring bipolar neurone, with which the rod cell synapses. The bipolar cell releases transmitter substance into its synapse with a neurone of the optic nerve. If sufficient transmitter is released, an action potential is generated in the neurone of the optic nerve and transmitted to the visual centre of the brain

32
Q

How do we explain summation (in the eye)

A

With low-intensity stimuli, generator potentials have an additive effect and there is enough transmitter released to reach threshold for an action potential to be generated in a neurone of the optic nerve

33
Q

What is dark adaptation?

A

Rhodopsin is resynthesized in the rods. this requires ATP from mitochondria. the rate of resynthesis is sufficient for the rods to continue functioning in dim light, but in bright light the rhodopsin is almost entirely bleached. It takes about 30 minutes in darkness for all the rhodopsin to be reformed and so for the rods to become functional, this is dark adaptation

34
Q

Describe what we see through succession

A

(Based off N. America) During pioneer stages we see lichens, then moss, then herbs and weeds. In the intermediate stages we see grasses, then shrubs, then pines, spruces, chestnuts and immature oaks. At the climax community we see oaks, hickories, chestnuts, maples

35
Q

What do we see in secondary succession?

A

annual plants, then grasses and perennials, then shrubs and small trees, then young woodland trees, and finally mature woodland at the climax

36
Q

What is zonation

A

Different communities are present at the same time, distributed as bands or zones along an environmental gradient

37
Q

How do we calculate efficiency of energy transfer>

A

(energy in one trophic level/energy in previous trophic level) x 1000