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External Revision:Biology > CB1: Key Concepts In Biology > Flashcards

CB1: Key Concepts In Biology Flashcards

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1
Q

What is a eukaryotic cell? Describe it.

A

A cell with a nucleus. It has a complex structure and can make up whole organisms.
Eg Palisade cells and somatic cells

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2
Q

What is a prokaryotic cell?

A

A cell with no nucleus. It has a simpler structure than eukaryotes and is unicellular
Eg Bacteria

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3
Q

Name and describe sub cellular structures of a somatic cell

A

Cell membrane- controls substances entering and leaving the cell

Ribosomes- work in protein synthesis (creating proteins) and translation of genetic material

Mitochondria- where most reactions for respiration happen: transfers energy for cell to work

Cytoplasm- where most chemical reactions happen. Enzymes contained in this gel-like substance aid and control these reactions

Nucleus- contains genetic material arranged into chromosomes and controls cellular activities

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4
Q

Name and describe sub cellular structures of a palisade cell

A

Ribosomes

Mitochondria

Cell membrane

Nucleus

Cytoplasm

Cell wall- made from cellulose. Maintains cell shape, strengthens it and supports it.

Chloroplasts- contain chlorophyll, a green protein that aids in photosynthesis (where food for the plant is made)

Large vacuole- where cell sap is stored, a weak solution of sugar and salts
Also maintains internal cell pressure which supports cell

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5
Q

How is an egg cell specialised?

A

Haploid nucleus is able to fuse with a sperm’s haploid nucleus to create a diploid zygote which has the right amount of genetic material

Has nutrients to feed and nourish the embryo or baby at the early stages of life

Has a jelly extracellular coat that provides chemoattractants and hardens once a sperm has fertilised it so more don’t enter

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6
Q

How is a sperm cell specialised?

A

Sperm have extra long tails to swim to the egg cell and fertilise it

They have haploid nuclei so that they can fuse with an egg cell’s nucleus and create a diploid nucleus for the zygote

There is an acrosome which contains enzymes which breaks down the ovum’s cell membrane and is able to fertilise it

It has many mitochondria in the middle section to provide energy through respiration for the sperm to be able to swim to the ovum

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7
Q

How are ciliated epithelial cells specialised?

A

Ciliated epithelials have cilia, hair like structures, which beat and move substances along tissue surfaces in one direction

Eg cilia are lined in the airways and waft mucus toward the throat so it can be swallowed and doesn’t go to lungs

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8
Q

How are root hair cells specialised?

A

They have a large surface area so they can absorb more water for the plant for respiration and photosynthesis

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9
Q

Name and describe features of a prokaryotic cell eg bacteria

A

Chromosomal DNA- large loop/strand which contains most cellular DNA and controls cell activities and replication

Flagellum- propels the bacterium from harmful substances like toxins and towards nutrients eg water and oxygen

Cell membrane
Ribosomes

Plasmidal DNA- extra loops of DNA. It can contain genes for drug resistance etc

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10
Q

Explain stages of examining a specimen under a light microscope

A

1) Take a clean slide and use a pipette to put a drop of distilled water on it so the specimen sticks onto it. Use tweezers to put the specimen on the slide.
2) Then stain it. You can use stains to highlight specific sub cellular structures eg methylene blue stains DNA and iodine stains onion cells
3) Place a cover slip over the specimen and press it down gently so no air bubbles appear on it
4) Clip the slide to the stage
5) Choose an objective lens to look through. You can use the coarse adjustment knob to move the stage up or down and the fine adjustment knob to make the image clearer

6) Look through the eyepiece lens to see in the FIELD OF VIEW.
Measure FOV with a clear ruler
It can change if you increase or decrease magnification with the objective lens.
Therefore you need to divide or multiply your field of view by how much the magnification has increased

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11
Q

What is the total magnification?

A

Total magnification = eyepiece magnification x objective lens magnification

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12
Q

How do you calculate magnification?

A

Magnification= image size / real size

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13
Q

How do you calculate image size?

A

Image size = real size x magnification

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14
Q

How do you calculate real size?

A

Real size = image size / magnification

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15
Q

How do you convert from mm to micrometres to nm to pm?

A

X1000 each time

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16
Q

How do you convert from pm to nm to micrometres to mm?

A

/1000 etc

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17
Q

What is an enzyme?

A

A biological catalyst- it speeds up reactions without changing or running out

18
Q

Describe the lock and key mechanism

A

An enzyme has a complementary active site to its substrate and is therefore able to catalyse the reaction

19
Q

What happens when the temperature/pH is over optimum?

A

The peptide chains that make up the enzyme unravel and the bonds break

TMT the active site of the enzyme is distorted which means that it is unable to catalyse the reaction and break down its substrate

20
Q

Stomach enzyme?

A

Pepsin: optimum pH is 2

21
Q

What is the use of electron microscopes?

A

Allow us to see specimens with a higher resolution and a clearer image

22
Q

What are the quantitative measurements for specimens

A

Milli 10^-3
Micro 10^-6
Nano 10^-9
Pico 10^-12

23
Q

What is the affect of substrate concentration on reaction rate?

A

Rate will go UP as the more substrate, the faster the reactions.

HOWEVER it will plateau as active sites can become saturated with substrate and be full, unable to speed up

24
Q

Core practical: pH affecting rate of reaction

A

Fill wells of spotting tile with iodine (to test for starch)

Get Bunsen burner and heat water until it’s 35 degrees

Add 3cm^3 of amylase solution and 1cm^3 of buffer solution with pH5 to a boiling tube

Put boiling tube in water and wait 5 mins

THEN

Add starch solution

Mix and turn on stop clock

Take sample of solution every 10 seconds and put in different well of spotting tile each time

You should see a gradual turning of blue-black iodine back to orangey brown, meaning there is a loss of presence of starch and that amylase has broken it down

25
Q

How to calculate rate of reaction

A

Rate= change/time

26
Q

What breaks down protein and what into?

A

Protease

Amino acids

27
Q

What breaks down fats and what into?

A

Lipase

Fatty acids and glycerol

28
Q

What breaks down carbohydrates/ starch and what into?

A

Carbohydrase/amylase

Simple sugars eg maltose

29
Q

How to test for protein

A

Biuret test

Add potassium hydroxide
Add copper(II) sulphate
Add test substance

If PURPLE, protein is present

If stays blue- not present

30
Q

How to test for fats

A

Emulsion test

Add to ethanol
Shake
Then add to water

If there is a milky precipitate on top, fat is present

31
Q

Test for starch

A

Iodine

If present: blue-black

If not: stays orange-brown

32
Q

Test for SIMPLE SUGARS

A

Benedict’s reagent

Tests for reducing sugars eg glucose, NOT SUCROSE

Produces coloured precipitate

Higher concentration-> higher up colour scale

Blue-green-yellow-orange-brick red

33
Q

Calorimetry

A

Burn dry food under water and measure starting and finishing temperature

34
Q

Equation for energy in food?

A

Energy in food= mass of water x water temp change x 4.2

35
Q

Equation for energy per gram of food?

A

Energy/gram= energy in food/mass of food

36
Q

What is diffusion?

A

The net movement of particles with the concentration gradient from an area of high concentration to an area of low concentration.

Only small molecules can diffuse eg oxygen and amino acids and glucose

Only happens with liquids and gases

37
Q

What is osmosis

A

The net movement of WATER MOLECULES through a PARTIALLY PERMEABLE MEMBRANE from a high concentration to low concentration

38
Q

What is active transport?

A

The net movement of particles AGAINST THE CONCENTRATION GRADIENT from a LOW to HIGH concentration

39
Q

Give an example of active transport

A

Gut gives blood sugar
This is vital for our nourishment and for respiration

Even if gut has LOW CONCENTRATION it still gives blood sugar with HIGH CONCENTRATION in order for us to avoid starving and survive

40
Q

Osmosis core practical

A

Potato cubes in increasing concentration of sucrose solution

SHOULD SEE

Potato mass increase in low concentration of sucrose: more water on the outside of potato that inside so water travels from the high-low concentration: potato mass increases

In high concentration of sucrose: potato mass decreases as more water on the inside of potato on outside so water travels from high to low concentration from potato to solution

41
Q

How to calculate percentage change in mass?

A

% change in mass= final mass-initial mass/initial mass

External Revision:Biology (2 decks)

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