Science - Cycle Test Term 1 Flashcards
1
Q
What does Magnification mean?
A
The number of time larger the image we see is.
2
Q
What is a Specimen?
A
The sample you are trying to see.
3
Q
What does resolution mean?
A
The detail shown in the image.
4
Q
Who created the first microscope?
A
Robert Hooke
5
Q
What is the eye piece lens
A
The first lens we look through.
6
Q
What is the objective lens?
A
The second lens that magnifies the image. You can rotate it for different magnifications.
7
Q
What is the stage?
A
The part that supports the specimen.
Adjustable distance to objects.
8
Q
What is a slide?
A
The piece of glass that holds the specimen.
9
Q
How do you calculate the magnification of an image?
A
Magnification of the eyepiece lens X Magnification of the objective lens = Magnification of the image
10
Q
What are ribosomes?
A
This is where protein is produced.
11
Q
What is the Nucleus?
A
The brain of the cell, controls the cell, it contains DNA (Genetic material).
12
Q
What is DNA?
A
Exists in the nucleus, it is in compact shapes called chromosomes.
13
Q
What are chromosomes?
A
The ‘X’ shape that DNA is stored in.
14
Q
What is a cell membrane?
A
Controls substances going in and out.
15
Q
What is a cytoplasm?
A
A jelly like substance where chemical reactions take place.
16
Q
What is a cell wall?
A
Protects the cell and maintains the shape of the cell.
17
Q
What is a mitochondria?
A
Where aerobic respiration takes place.
Bean shape.`
18
Q
What is a chloroplast?
A
Contains chlorophyll. This is where photosynthesis takes place.
19
Q
What is a vacuole.
A
Stores cell sap. It helps hold the cell together.
20
Q
What is cell sap?
A
Contains sugars, amino acids, waste substances (such as tannins), and mineral salts.
21
Q
What is chlorophyll?
A
A green substance that is in chloroplasts, that is needed for photosynthesis.
22
Q
What are the 2 types of cells?
A
- Prokaryotic cells
- Eukaryotic cells
23
Q
What is a prokariotic cell?
A
= A single celled organism.
- Are smaller and simpler
- No nucleus
- DNA is in plasmids
- Mainly bacteria
24
Q
What is a plasmid?
A
A small circular DNA molecule found in bacteria and some other microscopic organisms.
25
What is a Eukaryotic cell?
= Complex and include all animal and plant cells.
- Has a nucleus.
- More complex than Prokaryotes.
- Organelles
26
What is an oraganelle?
Subcellular structures.
27
What is a specialised cell?
Cells that are adapted to perform a certain job.
28
What is the adaptations of a specialised cell?
- Shape
- Size
- Structure
- Content
29
Provide some examples of specialised cells?
- Ciliated Epithelial Cells
- Red blood cells
- Root hair cells
- Sperm cells
- Egg cells
30
What are the adaptations of a sperm cell?
- Acrosome = it is at the front of the sperm's head and contains enzymes that digest the egg cells membrane.
- Long tail = To help the sperm swim to the egg cell.
- It has a lot of mitochondria, arranged in a spiral shape, at the top of the tail (middle section of the sperm) to provide the energy needed for the tail to swim.
- Has a haploid nucleus
- Streamlined shape to help it swim efficiently in the uterus.
31
What are the adaptations of an egg cell?
- Cytoplasm contains nutrients to feed the embryo.
- Has a haploid nucleus.
- Membrane changes structure straight after fertilisation to prevent any more sperm cells entering to ensure that the offspring end up with the right amount of DNA.
32
What are the adaption of a muscle cells?
- Many mitochondria as they need more energy than other cells.
33
What is digestion?
The process of breaking down the food to extract the nutrients.
34
What is a micronili?
A microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume.
35
What is a Gamete?
Reproductive cell.
36
What are some examples of gametes?
- Egg cells (Ovum)
- Sperm cell
37
What does fertilisation mean?
The process of the sperm and ell cell combining to form an embryo.
38
What is an enzyme?
Special substance that breaks down long molecule from the egg membrane fond at the top of the sperm cell.
39
What is a diploid nuclei?
A nucleus with a full set of chromosomes.
40
What is an epithelial cell?
- A cell that lines the surface of an organ.
- Some have cilia.
41
What is a haploid nuclei?
A nucleus with half the number of chromosomes as in a diploid cell.
42
What is cilia?
- A hair like structure on the top surface of a cell.
- In the uterus it moves the egg along the fallopian tube.
- In the nose and lungs it traps dust and dirt from entering during respiration.
43
What are the specialised cells for digestions?
- Cells in the small intestines have increased surface area for the absorption of nutrients.
- Microvilli (membrane with tiny folds) increase surface area.
- More ribosomes to produce more proteins to produce more enzymes to help digest and absorb food.
44
What is a ciliated cell?
A cell that has little hair like structures called cilia.
45
What is a acroscome?
The pointy tip of the sperm cell.
46
What is the plasmid?
- One loop of DNA
- Controls cell activities
47
What is the cytoplasm?
A jelly like substance where chemical reactions take place.
48
What is aa flagellum?
- Tail like structure that helps bacteria swim
- Many bacteria have them but not all
49
What is a ribosome?
- Produces proteins
50
What is a cell wall?
A flexible coat around the cell.
51
What do bacteria not have?
- Mitochondria
- Nucleus
- Chloroplast
52
What is the size growth from a cell to an organism?
Cells
Tissues
Organs
Organ Systems
Organisms
53
What is a cell cycle?
- Process that multicellular organisms go through to make new cells.
54
What is mitosis?
- Parent cells replicating into two identical 'daughter cells'.
- When a cell reproduces itself by splitting in two to form two identical offspring. It refers specifically to the splitting of the nucleus
55
What is genetic material?
Instructions for the cell to function and the body to grow and develop.
56
What is a chromosome?
A long length of DNA molecules coiled in a double helix.
57
Why do body cells replicate?
To repair damaged tissue and to grow.
58
How are cancerous tumours formed?
Rapid cell division can result in tumours and cancerous cells.
59
What is mitosis in some organisms?
Asexual reproduction
60
What happens in mitosis?
Parent cells duplicate.
61
What is a clone of the parent?
- An identical copy
- Parent cells duplicate by mitosis and form identical offspring.
62
What is the mnemonic for the stage of cell replication?
I = Interphase
Prefer = Prophase
Milk = Metaphase
And = Anaphase
Tasty = Telophase
Cookies = Cytokinesis
63
What are the phases of mitosis?
Prophase
Metaphase
Anaphase
Telophase
64
What happens in interphase?
Initially, the DNA is spread out into longs strands.
Before division the cell has to:
a) grow
b) increase the number of subcellular structures like the mitochondria and ribosomes
The DNA then replicates so that there is a copy for each cell of each chromosome. It forms an 'X' shape, each arm of the chromosome is the exact duplicate of the other arm.
65
What is a chromatid?
It is the name for each arm of the 'X' shaped DNA. Each are is a exact duplicate of each other.
66
What happens in prophase?
a) Chromosomes condense- get shorter and fatter
b) Membrane around the nucleus breaks down.
c) Chromosomes lie free in cytoplasm
67
What happens in metaphase?
The chromosomes line-up along the centre of the cell on the spindle fibres.
68
What happens in anaphase?
a) Spindle fibres pull the chromosomes apart.
b) The two chromatids of each chromosome are pulled to opposite ends of the cell.
69
What happens in telophase?
A membrane forms around each set of chromosomes to create two nuclei - one for each new cell.
70
What happens in cytokinesis?
The cell membrane forms to separate the two cells. This process begins before telophase ends.
71
What are the properties of the daughter cells?
a) Contains the same number of chromosomes as the parent nucleus.
b) Is genetically identical to the diploid parent cell.
c) Is a diploid cell
72
What is a spindle fibre?
It pulls the chromosomes to where they need to be.
73
What does the cell membrance do?
Controls the movement of substance in and out of the cell and keeps the shape of the cell.
74
What do the ribosomes do?
This is are involved in photosynthesis and is where the second stage of photosynthesis takes place.
75
What are the difference between prokaryotic and eukaryotic cells?
- Prokaryotes don't have a nucleus but eukaryotic cells do
- Prokaryotes don't have a mitochondria but eukaryotic cells do
- Prokaryotes don't have a chloroplasts but eukaryotic cells do
- Prokaryotes are small (0.1 to 5 nanometres) but eukaryotes are large cells (10 to 100 nanometres)
- Prokaryotes are always unicellular.
76
What do both prokaryotic and eukaryotic cells have?
- They both have cell membranes.
- They both have cytoplasm.
- Eukaryotic PLANT CELLS and prokaryotic cells have cell walls.
- They both have ribosomes.
77
What is a nucleus?
It contains genetic materials that control the activities of the cell. It is arranged in chromosomes.
78
What does the cytoplasm do?
This is a jell like substance where chemical reactions take place. It contains enzymes that control the chemical reactions.
79
What is a mitochondria?
This is where most of the reactions for aerobic respiration take place. A platform for breaking down nutrients and turning it in to energy.
80
What is a cell wall?
This is a rigid structure made of cellulose that supports and strengthens the cell.
81
What is a large vacuole?
It contains cell sap which is a weak solution of sugars and salts. I maintains the internal pressure to support the cell.
82
What is a chloroplasts?
Contains chlorophyll (a green substance which absorbs light needed for photosynthesis.) Chloroplasts are where photosynthesis occurs which makes food for the plant.
83
What is a bacteria cell?
- They are prokaryotes
- A bacterial cell has
a) Cytoplasm containing ribosomes, and
b) A cell membrane surrounded by a cell wall
84
How is the bacteria cell's activities and replication controlled?
- Bacteria cells do not have a nucleus
- It has a single circular strand of chromosomal DNA that floats freely in the cytoplasm controlling the cell's activities and replication
85
What are the sub cellular structures of a bacteria cell?
1. Cell wall
2. Cell membrane
3. Cytoplasm
4. Ribosomes
5. Flagellum (sometimes)
6. Chromosomal DNA
7. Plasmid DNA
86
What are plasmids?
It is a small loop of DNA that contain genes, for things like drug resistance, which can be passed between bacteria.
Plasmids are not part of the main chromosome.
87
What is a flagellum?
A hair like structure that is in some bacteria. It is used by the cell to help it move away from harmful substances like toxins and toward nutrients and oxygen.
88
What are the uses of mitosis?
- To help repair damaged tissues and cells.
- For the growth of multicellular organisms.
- For asexual reproduction(Offspring have the same DNA as its one parent, e.g. strawberry plants, potato plants and bambo, bananas, dandelions.)
89
What is asexual reproduction?
- It involves only one parent
- Therefore offspring are identical to parents
- It happens by mitosis
- An ordinary cell divides in 2 to make 2 genetically identical diploid cells which are identical to the parent cell.
90
What are the advantages of asexual reproduction?
- Only one parent is needed for the reproductive cycle.
- Faster
- More offspring in a short period of time.
- Organisms reproduce whenever the conditions are favourable.
- It allows the new organism to colonise the new area rapidly.
91
What are the disadvantages of asexual reproduction?
- All are no genetic variation in offspring in population or generational population.
- If the environment changes and the conditions are unfavourable the whole population cannot survive/ cope. (e.g. black sigatoka affects bananas)
92
What is cell differentiation?
The process by which a cell changes to become a specialist cell?
93
How do cells grow and develope?
- Cells grow my mitosis.
- Cell differentiation
- Cell elongations (PLANTS ONLY)
94
Describe the growth in animals?
All growth is via cell division
- When:
a) Young
- cells divide at a faster rate
- mainly for growth
- and some replacement
b) Adult
- Cells dived to replace old or damaged cells
- hence in animals, cell differentiation is lost at an early stage
95
Describe the growth in plants?
- Cell elongation
- Gives rise to the height of the plant and similar growth
- Controls the direction of growth, towards water and sunlight
- Cell division
-Usually happens at the tips of roots and shoots(the area called the meristem)
Plants are continuously growing in new flowering stems and branches on trees. A such plant continue to differentiate to develop new plants like leaves and routes throughout their life.
96
What is mutation?
It is a random change in a gene.
97
What controls the level of cell division and the rate at which it happens?
The body controls the level of cell division that happens for growth and cells tend to stop dividing when sufficient cells have been produced.
The rate of cell division by mitosis is controlled by the chemical instructions called genes in the organised DNA.
98
What is a tumour?
If a change arises in one of the genes that control cell division the cell may start dividing uncontrollably.
A tumour is the mass of abnormal cells resulting from a mutation to a gene that controls cell division causing the cell to start dividing uncontrollable
99
What is cancer?
Cancer is when a tumour invades and destroys surrounding tissue.
100
How are percentile charts used?
The charts can be used to asses growth over time and highlighting any problems like dwarfism, obesity and malnutrition.
For example a babies growth is monitored after birth by measuring their length, mass and head circumference.
101
What are stem cells?
All cells in organism originate from stem cells.
A stem cell is an undifferentiated cell which has not yet changed to become specialised for a particular function/ job.
102
How do stem cells differenticate?
Stem cells can divide to form lots of undifferentiated cells which can then specialise depending on their genetic instructions.
103
Where are stem cells found?
Stem cells are found
a. in early human embryos (these are embryonic stem cells which can divide and produce any kind of cell as such embryonic stem cells are really important for growth and development because they have the potential to divide and produce any kind of cell.)
104
Where can you find adult stem cells?
- They can be found in certain places like bone marrow
- These stem cells are not as versatile as embryonic stem cells as they cannot produce any cell type only certain ones like blood or new skin
105
Can adult cells be used to cure diseases?
Yes, they are currently used to cure diseases like
-Sickle cell anaemia
106
What are the used of stem cells in medicine?
Scientist have identified that embryonic stem cells can be stimulated to differentiate into specialised cells.
This means that there is the potential for replacing faulty cells with embryonic stem cells. E.g. Insulin producing cells for people with diabetes, and nerve cells - to replace damaged spinal tissue in people paralysed by spinal injuries.
107
What is the advantage of embryonic stem cells over adult stem cells?
- Embryonic stem cells can be differentiated for many types of cells unlike adult cells.
- Embryonic stem cell are easier to grow in culture than adult stem cells.
- The is less likely chance of rejection if own stem cells are used.
108
What are the issues of using stem cells?
- Before using specialist stem cells a lot of research needs to be performed due to numerous risks like
a. tumour development - if scientist are unable to control the rate at which the stem cells divide in a patient
b. diseases transmit - viruses live inside cells and may not be detected if the donor cells are infected and could be passed on to the recipient making them more sick.
c. rejection - if the stem cells are not the patients own stem cells their body may recognise these as foreign cells tiggering an immune response.
- Ethical issues
-Obtaining stem cells from embryos destroy the embryo which is seen by many as a life form.
- In some countries stem cell research is banned while others like the UK allow it under strict guide lines being followed
109
What are immumo-represents?
Immuno-represent can be used to supress the immune response but make the patients susceptible to other diseases.
110
What are stem cells in plants?
Plant cells that divide by mitosis are found in plant tissue called meristems.
111
Where are meristem tissues found?
In areas where plants continue to grow.
E.g. Tips of routes and shoots.
112
What are meristem cells?
They are unspecialised cells that can divide and form any other plant cell type. They only divide by mitosis.
They are the equivalent of embryonic stem cells.
113
What are the difference between embryonic stem cells and meristem cells?
- Meristem cells can divide and differentiate as long as the plant lives, adult stem cells are unable to achieve this.
114
What tissue do unspecialesed plant cells form?
Them form specialised tissue like xylem and phloem.
115
What does DNA stand for?
Deoxyribonuceic Acid
116
What is DNA?
A chemical that contains coded information of the genetic material in a cell
117
Where is DNA found?
In the nucleus of eukaryotic cells in long structures called chromosomes.
The DNA is coiled up to form they 'arms' of the chromosome which in diploid cells, come in pairs.
118
What is a chromosme?
A long coiled up molecule of DNA which carries the genes.
119
What is a gene?
A small section of DNA that codes for a particular sequence of amino acids which are put together to make a specific protein.
120
What is the genome?
It is all the genetic material in an organism.
121
What are alleles?
It is an alternative version of a gene.
122
What are homozygous?
Where an organism has 2 alleles for a particular gene that are the same and the characteristic is controlled by a single gene.
123
What is a heterozygous?
Where a characteristic is controlled by a single gene and an organism has 2 alleles for that particular gene that are different.
124
What is a dominant allele?
The allele for a characteristic that is shown by an organism if two different alleles are present for that characteristic.
Capital letter are used for dominant alleles.
125
What is a recessive allele?
An allele whose characteristic is only appears in an organism where there are 2 copies of the allele present.
Lower case letter are used for recessive alleles.
126
What is a genotype?
It is the combination of alleles you have.
E.g. AA or oo or Ao.
127
What is phenotype?
This is the characteristic the organism has.
E.g. Black hair, blue eyes, A blood group
127
What are Mendel's conclusions?
- Characteristic in plants are determined by hereditary units/genes.
- Hereditary units are passed from both parents (one from each parent) to offspring UNCHANGED.
- Hereditary units can be dominant or recessive.
128
Why was Mendel's work important?
Because it was very advanced and cutting edge, it was also knew to scientist at the time and lay the foundation for the mechanism of inheritance that we know today.
His hereditary units are now known as genes.
