biology year 9 exam rev

Question 1

what is a cell?

Answer 1

the building block of all living things

Question 2

what is an organelle?

Answer 2

EG.
cell membrane
cell wall
cytoplasm
mitochondria
nucleus
chloroplasts
ribosomes
endoplasmic reticulum
golgi body
vacuole

Question 3

plant cells that are absent in animal cells

Answer 3

cell wall
chloroplasts
multiple small vacuoles

Question 4

function of the mitochondria

Answer 4

powerhouse of the cell

Question 5

function of the chloroplast

Answer 5

found only in plant cells
the site of photosynthesis

Question 6

function of the cell wall

Answer 6

found only in plant cells
protects the cell and gives it support

Question 7

function of the cell membrane

Answer 7

all cells have a cell membrane
control what goes in and out of the cell

Question 8

function of the cytoplasm

Answer 8

all cells have a cytoplasm
the site of chemical reactions
jelly - like fluid

Question 9

function of the ribosomes

Answer 9

found in all cells
produces proteins

Question 10

function of the endoplasmic reticulum

Answer 10

• can be smooth, (no ribosomes attached)
  can be rough (ribosomes attached)

Question 11

function of the golgi body

Answer 11

modifies and packages proteins

Question 12

function of the vacuole

Answer 12

storage space for water, food and waste
one large vacuole in plant cells
many smalls vacuoles in animal cells

Question 13

what is dna?

Answer 13

• the universal code of life
• stands for deoxyribonucleic acid
• a molecule
  -double stranded

Question 14

dna molecule

Answer 14

dna is a very large molecule made up of a long chain of subunits
- each subunit is called a nucleotide

Question 15

nucleotide

Answer 15

always a:
phosphate, nitrogenous base and a sugar (deoxyribose)

Question 16

nitrogenous base

Answer 16

adenine, cytosine, thymine, guanine
(A-T) (G-A)

Question 17

joining nucleotides

Answer 17

to join together, the phosphate from one nucleotide forms a bond with the sugar on the next.
- this forms the sugar - phosphate backbone.

Question 18

where are the sugar phosphate backbones

Answer 18

on the outside, held together y hydrogen bonds

Question 19

what is the double helix

Answer 19

the 3d shape of dna is called the double helix.

Question 20

what are genes?

Answer 20

• a segment of dna that codes for proteins
• these proteins determine your trait (such as hair colour, eye colour, skin colour)

Question 21

what are chromosomes

Answer 21

• each chromosome is a different size and has a different number of genes.
• inherited equally from your parents
• avergae human body cell has 46 chromosomes
  -23 from mum, 23 from dad

Question 22

what is homologous pairs

Answer 22

two copies of every chromosome

Question 23

wat is diploid

Answer 23

contains two copies of every chromosome

Question 24

what is haploid

Answer 24

contains one copy of every chromosome

Question 25

what is a karyotype

Answer 25

- XX female XY male a karyotype is a picture of all the chromosomes in a cell, arranged in pairs. - they are arranged in the order of size - first 22 pairs are autosomes (non - sex chromosomes - and pair 23 are the sex chromosomes

Question 26

what is homologous chromosomes

Answer 26

- size - banding pattern - centromere position helps scientists to identify a karyotype

Question 27

trisomy 21

Answer 27

- 47 chromosomes - down syndrome - almond shaped eye, short limbed

Question 28

klinefelters syndrome

Answer 28

xxy - 47 chromosomes - only in males - tall, small testicles, appear normal

Question 29

turner's syndrome

Answer 29

single x in female - 45 chromosomes - short webbed neck

Question 30

what is an allele

Answer 30

different versions of the same gene. eg. B = brown eye colour b = blue eye colour

Question 31

what is genotype

Answer 31

the particular combination of alleles in a gene genotypes can be: homozygous (two of the same allele eg. BB or bb) heterozygous (one of each allele eg. Bb)

Question 32

what is a phenotype

Answer 32

the visible expression of a genotype (how this gene affects the way you look or how your body changes) phenotype = genotype + environment

Question 33

what is a trait

Answer 33

is the name of a genetically determined characteristic such as height, eye colour, hair type, etc. - traits can be dominant or recessive

Question 34

examples of dominant traits

Answer 34

eg. pigmented skin widows peak brown eyes rolling tongue free earlobes

Question 35

examples of recessive traits

Answer 35

eg. attached ear lobes red hair blue eyes colour blindness

Question 36

what is a carrier

Answer 36

- people that are heterozygous can also be called carriers - carriers have an allele for the recessive trait in their genotype

Question 37

what is a punett square

Answer 37

- to determine if the trait will be passed on - punnett square is used to predict inheritance

Question 38

pedigree symbols

Answer 38

- males are represented as squares - females are represented as circles - gender none specified is represented as a rhombus - filled symbols show who exhibit the trait

Question 39

interpreting pedigrees

Answer 39

- must determine whether the trait is dominant or recessive.