Biology #5

Question 1

Disadvantage of asexual reproduction

Answer 1

• offspring all genetically identical
• no genetic variation

Question 2

Define asexual reproduction

Answer 2

as a process resulting in the production of genetically identical offspring from one parent

Question 3

Advantage of asexual reproduction

Answer 3

• faster reproduction
• requires less energy

Question 4

What type of organisms can produce asexually

Answer 4

Mainly bacteria, fungi, small plants/animals, potatoes and bulbs

Question 5

Define sexual reproduction

Answer 5

as a process involving the fusion of the nuclei of two gametes to form a zygote and the production of offspring that are genetically different from each other

Question 6

Gametes

Answer 6

Gametes are formed by meiosis, a type of cell division which produces cells with half the chromosome number

Question 7

Advantage of genetic variation in the wild

Answer 7

Genetic variation means that organisms can better survive changes to the environment. Some individuals may die, but as the population is genetically diverse some will have the traits to survive

Question 8

Vantages of genetic variation in crops

Answer 8

Having crop plants that are genetically different is important for ensuring the crop can survive environmental change

Question 9

Male part of a flower

Answer 9

Stamen - consists of filament (long, thin) and anther (pollen)

Question 10

Female part of a flower

Answer 10

Carpel – consists of stigma (sticky
opening), style (long tube connecting stigma to ovary), ovary (houses ovules; becomes fruit), and ovules (develops female gametes; become seeds)

Question 11

Define pollination

Answer 11

As the transfer of pollen grains from an anther to a stigma

Question 12

Define self pollination

Answer 12

As the transfer of pollen grains from the anther of a flower to the stigma of the same flower or a different flower on the same plant

Question 13

Cross pollination

Answer 13

As the transfer of pollen grains from the anther of a flower to the stigma of a flower on a different plant of the same species

Question 14

Define STI

Answer 14

As an infection that is transmitted through sexual contact

Question 15

HIV

Answer 15

• HIV is a pathogen that causes an STI
• HIV infection may lead to AIDS

Question 16

Different ways HIV is transmitted

Answer 16

• unprotected sex
• organ transplant
• blood transfusion
• pregnancy breastfeeding
• use of non sterile syringes and tools

Question 17

Ways to reduce the spread of HIV and other STI’s

Answer 17

• use a condom during sex
• avoid breastfeeding if you are HIV positive
• don’t share needles for injecting drugs
  -make sure you check if someone has an STI before sex

Question 18

FSH

Answer 18

• stimulates egg maturation in the follicles of the ovary
• stimulates follicles in the ovaries to secrete oestrogen

Question 19

LH

Answer 19

• At its peak stimulates ovulation (release of egg into oviduct)
• results in the formation of a corpus luteum

Question 20

Oestrogen

Answer 20

• stimulates the uterus to develop a lining (to replace the lining lost during menstruation)
• post ovulation, inhibits FSH and LH production in the pituitary gland

Question 21

Progesterone

Answer 21

• maintains and thickens lining of the uterus
• inhibits FSH and LH production
• if fertilisation doesn’t occur, levels drop and menstruation occurs

Question 22

Define inheritance

Answer 22

The transmission of genetic information from generation to generation

Question 23

DNA

Answer 23

Chromosomes are made of DNA which contains genetic information in the form of genes

Question 24

Genes

Answer 24

As a length of DNA that codes for a protein

Question 25

Define allele

Answer 25

as an alternative form of a gene

Question 26

Diploid

Answer 26

99.9% of the cells in your body contain two copies of each chromosome. These cells are known as diploid cells.

Question 27

Haploid

Answer 27

The only cells with one copy of each chromosome are sex cells (sperm, eggs, pollen). These are known as haploid cells.

Question 28

DNA expession

Answer 28

All our cells contain the same genes, the only difference between them is which genes they express (i.e. produce proteins from)

Question 29

Variations of genes - alleles

Answer 29

Most genes will have multiple variations between people in their sequence. These are known as Alleles. Everyone has two alleles for each gene, one on each chromosome.

Question 30

The central dogma of biology - dna to rna to protein

Answer 30

Once we transcribe our DNA into mRNA it is sent to ribosomes in the cytoplasm - Ribosomes read the sequence of nitrogenous bases and translate it into a specific sequence of amino acids, forming a protein - 3 bases = 1 codon = code for 1 amino acid

Question 31

Seed requirements for germination

Answer 31

Germination = a seed sprouting * Germination requires 3 factors: Water (needed to soften seed) Suitable temperatures (makes sure it is the right time of year to sprout) Oxygen (needed for respiration to produce energy for cell division)

Question 32

How proteins are made

Answer 32

DNA always remains in the nucleus * DNA is copied to form mRNA (messenger RNA) in the nucleus Ribosomes convert the genetic sequences into a chain of amino acids which folds to form a protein

Question 33

Mitosis

Answer 33

Cell division giving rise to genetically identical cells * Used for growth, repair, replacing cells and asexual reproduction * During mitosis the DNA/ chromosomes replicate (makes a copy of itself), then the cell divides * Half the chromosomes will move into each divided cell, creating two Daughter cells with the same chromosome as the original parent cell

Question 34

Meiosis

Answer 34

Used for making sex cells / gametes. Only occurs in testes in males and ovaries in females * Produces 4 haploid daughter cells with half the chromosome number of a regular body cell * This is because at fertilisation the two haploid gametes will fuse, making the zygote diploid

Question 35

Stem cells

Answer 35

* Unspecialised cells that can divide by mitosis to become specialised cells

Question 36

Co dominance

Answer 36

Both alleles in a heterozygous organism are expressed in equal parts on the organism The alleles do not blend, but are both expressed at the same time

Question 37

Multiple allele traits

Answer 37

Involves genes that have more than two different alleles * Possible blood types: A, B, AB or O * Order of dominance: IA is equal dominance to IB (an example of codominance) IA and IB are dominant over IO

Question 38

Linked traits

Answer 38

* Traits that are “linked” are found on the same chromosome. This means they tend to be inherited together more frequently than by random chance

Question 39

Sex linked traits

Answer 39

Sex linked traits is where the gene for a specific phenotype is located on a sex chromosome * Males are much more likely to express a recessive phenotype for sex length traits e.g. pattern boldness green – red colour blindness